Because graphical power =/= generational leap.

It plays games the previous gen could not and can handle AAA ports of current gen games on the go natively.  No other console can do this.

Call it a handheld, but the games are still current gen console caliber  making that a pointless reach of an argument.  The Switch has features that previous generations did not have and current generations can only emulate under specific conditions (remote play).  The feature set along with the games it offers makes it next gen.

With that in mind, the whole generation thing has been blurred since PS3 to PS4, since for 2 years most games were cross gen.  At this point, labeling generations in of itself has become pointless as well.

But why are people defining Switch gen placement based on Sony/MS, and not the other way around?Why are people defining when a gen starts or ends when Sony releses a new console?(Im saying this based on reactions through the internet)

Just because its competing with the PS4/XOne dosent mean it belongs to the 8th gen, the same way that the PS3 and 360 opnce competed with the Wii U and werent a gen 8 console.Nintendo made a new console, which runs games that are exclusive to its system, which cant be played anywhere else(Its cartriges only work on the Switch).It launched betwenn 4 and 5 years since the Wii U first launched.Its a new generation through and through.

If we start defining a new generation based either on the number of years it took to release, or based on the competition, defining gens its gonna be a mess.What if PS5 is a giant commercial failure and Sony decides to release the PS6 in 4 or 5 years time, right in the middle of the other consoles lifespan?Gern 9.5?Gen 9.8?See what a mess that would make?

It’s the nineth gen. It’s really a simple concept.

Virtual Boy is not a handheld. A portable? Sure. But not a handheld.

Generations are based on time of birth and succession.  I am not just talking about video games.  I am talking any context.  How do you decide if someone is Baby Boomer, Gen X or Millennial?  Just look up the year they were born.  It's that simple.  Also, Gen X is the successor to the Baby Boomer generation, and Millennials are the successor to Gen X.  After a reasonable amount of time (depending on context), people decide its time to declare the next generation has started.

So how has this worked for video games?  The best way to describe it, is to look what happened going from generation 3 to generation 4.  In generation 3, Sega released the Sega Master System in 1986 (North America).  It was a commercial flop against the NES, so they scrapped it early and released the Sega Genesis in 1989 (just 3 years later) to compete directly with the NES.  It was even in their marketing "Genesis does what Nintendon't".  This isn't referring to Nintendo the company, but Nintendo the console.  The NES was called the Nintendo.  They were saying, "Our 16 bit console can do things that their 8 bit console can't do."  The Genesis competed directly with the NES for two full years, until Nintendo released the SNES in 1991.

So, given all of this evidence that the Genesis tried its hardest to be in generation 3 and compete with a generation 3 console, does that make it generation 3?  Nope.  None of that bullshit matters.  Generation is defined by time of birth and succession.  The Genesis was the successor to the SMS, so it was next gen even though it didn't want to be.  Also, the time of "birth" of Genesis and SNES was two years apart which made them closer in age to each other than the Genesis and NES.  The Genesis and SNES competed against each other directly the most years on the market as well. 

So here are the lessons we can learn about generation:

1) The first successor to market starts the next generation - Genesis started generation 4 (1989, NA), because it succeeded the SMS (1986).  Likewise Sega Saturn started generation 5 (1995), and Dreamcast started generation 6 (1999), because these were all the first successors to market.  Then Nintendo quickly released the DS in (2004) to make them first successor in generation 7, the 3DS started generation 8 (2011), and the Switch started generation 9 (2017). 

2) Power of the console doesn't matter - The Saturn and PS1 only had 32 bits.  The N64 had 64 bits.  They were all in the same generation, because power doesn't matter.  The Wii was much less powerful than the XBox360 and PS3.  The NES had the exact same processor as the Atari 2600.  None of this matters, because power doesn't matter.  Time of birth and succession is what matters.

3) First console for a company is decided by time of birth - The Turbographix-16 and original XBox were placed in generations 4 and 6 respectively, because their time of birth was closest to the other consoles of generations 4 and 6 respectively.

4) Consoles of different generations can compete with each other - The Genesis was made to compete with the NES.  The XBox360 competed mostly with the PS2 for its first couple of years on the market.  None of this matters for generations.  Time of birth and succession are what matter.

5) Upgrades don't matter - Consoles always get revisions and upgrades during their generation.  Nintendo especially does this with their handhelds.  The DS, DS lite and DSi are all part of the DS generation.  The New 3DS is a lot more powerful than the original DS.  This doesn't matter one bit.  Upgrades don't matter.  Time of birth for the first version is what matters.

6) The winner of one generation doesn't choose when the next generation starts - Nintendo learned this lesson the hard way.  They let their competitors release first in generations 4 and 5 and gradually they noticed that this was losing them market share.  It's the first successor to market that begins the generation.  Likewise, Sony doesn't dictate when generation 9 begins.  Nintendo had the first successor to market, so they have started generation 9 with the Switch.

Generation 9 has already begun with the Switch.  The first successor to market always starts the generation.  If PS5 comes out in 2019, then this will actually be very similar to what has happened before and it will naturally be in generation 9 with the Switch.  If PS5 waits a super long time, like 2021, to release then we will be entering new territory, and it will be likely placed in generation 10.  

The Atari 2600 is considered a 2nd generation console.
The Atari 5200, its successor, released 5 years after the 2600, is considered.... a 2nd generation console

So honestly who cares? This who "generation" nonsense is completely made up, doesn't follow any rules, and never has.

Switch will throw the whole generational thing down the toilet I'd bet. Switch Pro will come in a couple of years and then people will have all sorts of headaches trying to classify it.

Perfect! 

I assume the Switch is meant to compete with the Ps4 and XBOX 1, Though the WiiU was supposed to compete in that gen too. Nintendo has always been a gen behind since 2006. A docked switch is probably .5 gen behind the base Ps4 and XB1 but with the Pro and X out they are behind again. To be Fair BotW to me was superior to HZD even if graphically HZD was clearly a gen ahead. Since the Wii days Nintendo has a way to somehow deliver games that compete against AAA releases on more powerful hardware. But yeah they are a gen behind IMO.

This.
I dont get why its even a argument what generation it belongs to, its 8th gen.