The Switch actually has good third party support and sales. It's just not the same kind of support PS and Xbox have.

Ok, so just say it, you wanna move the goalpost because third parties isn't just about  AAA games, even you yourself value them more, this has no bearing on the fact the Switch has enjoyed a success among Indies and AA 3rd party games that it's console competitors do not on the same level. 

As for the AAA perspective, it is partially right in it's own accord that playing most 3rd party games on the Switch is already difficult due to the increasingly old hardware architecture that demands to restructure those games to be available on the platform to begin with. Yet, speaking of % of sales for these AAA games, there's precedent for the Switch versions of these games to surpass easily the Xbox sales, what do we about these ? Do we just say these games should not be ported on Xbox for the same reason you cited for the Switch ?

I think we need to understand what constitutes a 3rd Party Game?

Is it AAA developers, or does it include indie companies as well, or child companies?

Lifetime Sales Predictions 

Switch: 160 million (was 120 million, then 140 million)

PS5: 130 million (was 124 million)

Xbox Series X/S: 54 million (was 60 million, then 57 million)

"The way to accomplish great things, is to be indefatigable and never rest till the thing is accomplished." - Joseph Smith Jr.

Not at all.  I meant AAA in my post, I simply wasn't clear.  It was an honest omission that people are overreacting to.  I hate GTA and think Hades and Ori are some of the best games ever.  I'm currently playing Cocoon.  Oh and Tunic was super good too.  

So no, your take is wholly inaccurate.

Oh, and Triangle Strategy is the best square game in a decade.  

Porting indies is easier than AAA.  AAA on the switch, or lack of, makes sense.

Fair enough, nonetheless the discussion was about the 3rd party games in general so coming with the reclusive take on AAA games sales to determine success was not it.

Just throwing this in, but I think re are de-railing from what the thread creator originally asked.
This is not about Switch only. Heck, I'd argue that this thread is not about the Switch at all, because the heading is clearly using past tense.

All this talk of sales does make me want to point out we're assume that 3rd parties don't have a responsibility to make products that sell on successful platforms.

If there is a successful platform, shouldn't they be a part of it and figure out how to make it work for them?

You'd normally expect them to do so, yes. But what if that process turns out to be such a deviation from what kind of game(s) they would develop normally, that they basically have to turn them into exclusives or games that dont really appeal to the audiances of the other systems?

Then you run into the very same problem once again, where you have to compare two (or more) alternative investments. And thus far, reality suggests, that this comparison seems to turn out negative for the switch in almost all cases.

Funny side note by the way:

MH Rise seems to sell ~ 5,5 to 8,9% better per year and system compared to MH World thus far launch alligned.

Not if it doesn't fit into their longterm strategic pipeline. 

If someone is highly successful at writing huge series novels....  they should switch to short stories because novellas are a successful platform?

The question isn't if the switch is successful, the question is does the switch fit into any given developer's strategy.  

And making a game run on PC, ps4, ps5, Xbox one and series is easy.  Engines scale.  Porting to the switch is much harder.....  I hate to point out the PC, ps4, ps5, Xbox one and series x have more total sales than the Switch my a massive margin.

Probably worth noting a game can take 5 to 6 years to develop. So if production started in 2019 with Playstation in mind, moving to another platform like the Switch isn't exactly simple.