It matters to me, because I think it helps make predictions and accurate analysis.  For example, I am predicting that PS5+Series X will sell significantly less than PS4+XB1.  Why?  Because I think a lot of those sales are going to the Switch instead.   I am viewing generations as describing meaningful phenomena and not just an arbitrary way of categorizing things.

Now, if PS5+Series X sells about the same as PS4+XB1, then I will have to reevaluate my thinking.  That is just basic scientific reasoning.  But if my prediction is correct, then my view is the most logical explanation, that Switch is a Generation 9 system competing with the other Generation 9 systems.  Again, that is just basic scientific reasoning.

Generations are references to time, therefore technical limitations have nothing to do with it.  The majority of the WiiU's life was set in the 8th generation, and it is likely that the majority of the Switch's will be in the 9th generation.  If the Switch is cut short for whatever reason, I will eat crow but as it stands now it will be the Switch that not only succeeds the WiiU (8th gen) but also Nintendo's device on the market with the PS5 and XSX (9th gen).

Now you can say the definition of a generation does not matter to you, but then one would wonder why you are in a discussion about generations to begin with.

 Didn't we do this already or was that someone else?

At any rate, that's not really scientific reasoning... You're skipping from observation (XBoxX and PS5 sole more/less than their predecessors) to your explanation (Switch caused/didn't cause the decrease) without actually justifying why that's the explanation. There are many other possible reasons why they may do better or worse than their predecessors.

Moreover, how does calling Switch a gen 9 console help you make a prediction? If the word generation never entered the gaming lexicon, and we simply evaluated how systems will compete or not compete based on factors such as marketing, price point, features, and specs, would your prediction be any different? If not, what is generation adding to the conversation?

Correct, they are references to time. - And what is also a reference to time? Technological trends.

The 7th gen was most certainly defined by IBM Multi-core PowerPC as the processor of choice for consoles. - Playstation 3, Xbox 360, WiiU all fall into those category's. - IBM PowerPC fell out of favor due to the slow performance increase cadence and costs for the 8th gen.

The 8th gen is defined by hardware with universal pixel shader pipelines, tessellator units and more.

The 6th gen was defined by TnL or other fixed function light setup engines.

And you are also correct, the definition of a generation doesn't matter to me... I would also put forth the argument it doesn't matter to you either, it likely doesn't affect any of our purchasing decisions at the end of the day.

Well, let's explicitly spell out what scientific reasoning looks like.  The first thing is that scientific reasoning uses Occam's Razor which means that "the simplest explanation is most likely the right one."  If one says "systems are selling this way because they are in the same generation", it is simpler than saying "systems are selling this way because of a variety of factors such as marketing, price point, features, and specs".  The simpler explanation is most likely the correct one.  That is why I am talking about generations.  In fact one reason people practice science and develop theories is to give a simple explanation for phenomena that appear complex.  A key part of scientific reasoning is to keep things simple while still taking all of the data into account.

Secondly, the scientific method can basically be described using the following steps.
1. Do Research
2. Ask a Question
3. Form a Hypothesis 
4. Make a Prediction Based on the Hypothesis
5. Test the Prediction
6. Use the Results to Make More Hypotheses.
(With the understanding that a correct prediction means the hypothesis is strengthened while an incorrect prediction means the hypothesis needs to be changed.)

So, I actually use this process a lot when studying the video game industry.  There are some ideas that I am confident with and others where I had to change my thinking.  Here is one relevant example of a prediction I made about 7 years ago.

1. Research - There is a ton of past data on game sales to study.  I've looked at plenty and also read books on video game history, etc....
2. Question - Why is it that some systems for sale at the same time seem to compete with each other and others do not?  For example why did the Genesis/Megadrive compete with the SNES and not the NES when all 3 were for sale for many years together? 
3. Hypothesis - Systems need to be in both the same generation in order to compete with each other.  Generations need at least 4 years before the next one begins, and they begin when the first console maker releases a successor. (This is all based on previous observation.)
4. Prediction - Sales for Generation 8 systems will be similar to sales for Generation 6 systems.  Specifically, PS2+GC+XB = WiiU+PS4+XB1 with a margin of error of +/-20%.  (Generation 7 seemed to have a lot of customers that came and left, so it is left out.)  Any system released 2016 or later will be considered part of the next generation.
5. Test the Prediction - Basically I wait and see until all of the systems have stopped selling.  Although at this point, I'm fairly confident that my prediction will be correct.  (There is also a bunch of specific analysis I could do both here and for #4, but for now I am keeping it simple.)
6. Results - The generation system explains the market data pretty well.  We are also far enough along in time that I am now confident in putting Switch in Generation 9, the next generation.  Predictions that I make going forward will be based on this.

When I am talking about scientific reasoning, this is the sort of thing I am talking about.  Of course people can, and will, quibble about the details, but this is a solid framework to go by when analyzing the data.

Well, let's explicitly spell out what scientific reasoning looks like.  The first thing is that scientific reasoning uses Occam's Razor which means that "the simplest explanation is most likely the right one."  If one says "systems are selling this way because they are in the same generation", it is simpler than saying "systems are selling this way because of a variety of factors such as marketing, price point, features, and specs".  The simpler explanation is most likely the correct one.  That is why I am talking about generations.  In fact one reason people practice science and develop theories is to give a simple explanation for phenomena that appear complex.  A key part of scientific reasoning is to keep things simple while still taking all of the data into account.

Secondly, the scientific method can basically be described using the following steps.
1. Do Research
2. Ask a Question
3. Form a Hypothesis 
4. Make a Prediction Based on the Hypothesis
5. Test the Prediction
6. Use the Results to Make More Hypotheses.
(With the understanding that a correct prediction means the hypothesis is strengthened while an incorrect prediction means the hypothesis needs to be changed.)

So, I actually use this process a lot when studying the video game industry.  There are some ideas that I am confident with and others where I had to change my thinking.  Here is one relevant example of a prediction I made about 7 years ago.

1. Research - There is a ton of past data on game sales to study.  I've looked at plenty and also read books on video game history, etc....
2. Question - Why is it that some systems for sale at the same time seem to compete with each other and others do not?  For example why did the Genesis/Megadrive compete with the SNES and not the NES when all 3 were for sale for many years together? 
3. Hypothesis - Systems need to be in both the same generation in order to compete with each other.  Generations need at least 4 years before the next one begins, and they begin when the first console maker releases a successor. (This is all based on previous observation.)
4. Prediction - Sales for Generation 8 systems will be similar to sales for Generation 6 systems.  Specifically, PS2+GC+XB = WiiU+PS4+XB1 with a margin of error of +/-20%.  (Generation 7 seemed to have a lot of customers that came and left, so it is left out.)  Any system released 2016 or later will be considered part of the next generation.
5. Test the Prediction - Basically I wait and see until all of the systems have stopped selling.  Although at this point, I'm fairly confident that my prediction will be correct.  (There is also a bunch of specific analysis I could do both here and for #4, but for now I am keeping it simple.)
6. Results - The generation system explains the market data pretty well.  We are also far enough along in time that I am now confident in putting Switch in Generation 9, the next generation.  Predictions that I make going forward will be based on this.

When I am talking about scientific reasoning, this is the sort of thing I am talking about.  Of course people can, and will, quibble about the details, but this is a solid framework to go by when analyzing the data.

Correct, they are references to time. - And what is also a reference to time? Technological trends.

The 7th gen was most certainly defined by IBM Multi-core PowerPC as the processor of choice for consoles. - Playstation 3, Xbox 360, WiiU all fall into those category's. - IBM PowerPC fell out of favor due to the slow performance increase cadence and costs for the 8th gen.

The 8th gen is defined by hardware with universal pixel shader pipelines, tessellator units and more.

The 6th gen was defined by TnL or other fixed function light setup engines.

And you are also correct, the definition of a generation doesn't matter to me... I would also put forth the argument it doesn't matter to you either, it likely doesn't affect any of our purchasing decisions at the end of the day.

*facepalm*

The fact that you argue like this.
Playing devils advocate to yourself, with easily answeared questions by yourself, ignore all others (posted by other people).
And then conclude, your deduction must be right.... so its 9th gen.

You could just as well have said "it is, because I say so", its just as meaningfull.

You going to "the scientific methode", and useing it like this.
Uhuh, sure.


Instead of that foolery... how about answearing this (pemalite's raised point):

Generations are defined by the technology and capabilities/funktions they have.

9th gen will be about SSDs, hardware Raytraceing, 3D raytraced binaural sound ect.

Does the Switch do that?
Does it have more in common (from a technology stand point) with 8th gen?

*edit:
also power does need a mention, generations need to be somewhat close to one another (for consoles to belong to same generation).
PS5 is like ~30 times more powerfull than the Switch, and the Xbox Series X even more so.

What other generation, had 2 differnt consoles, belong to the same generation, were there was like a 30 times differnce in power between them?