Me saying PS4 is like Nintendo games about selling in no way means that Switch can't be the same or even better in doing the same. One thing doesn't invalidate the other. My comment was about a discussion i had yesterday about how much Nintendo games tend to keep their initial price because they keep selling and selling through the years (important aspect here..., years), and it came to my mind that with PS4 is a very similar thing too, but just with consoles. I don't know why should i need to name Switch in here at all. It's like to say that Zelda sells like Mario Kart and you come to me and say to me, "but it's Mario 3D game the one who is more close to sales to Mario Kart than Zelda!", well, yes..., or maybe not, but the original point still stands.
In regards of the second point. Yes, KH 3, The Division 2, MK 11 have sold a lot too, yes, but you even admit yourself, this year we have not seen really a system seller like MH World, Far Cry 5, God of War, Horizon Zero Dawn, Fortnite, ....It's a general consensus by almost everyone that 2019 has been worse than 2017 and 2018 in the same period. I don't think i'm lying in this regard. The rest of the year is going to be better, yes, but still nothing compared to the caliber of 2018 juggernauts like Spider-Man or Red Dead Redemption II.
It's just that i expected better quality games (critically i mean) in 2019 at the start of the year for PS4 to reach the numbers i expected by the end of the year, but it seems it wasn't as necessary. And yes, i agree with you, the main reason PS4 is selling less this year is saturation. That's what it makes this year sales so impressive. No home console (or if you prefer, console as a whole) has done 15M+ in a year after 5-6 years since launch still at 300$ or more. PS1, PS2 and Wii (and here i making a direct comparison indeed) were not able to do that, and DS was never as expensive.
I agree the original point still stands, but to be fair comparing a Nintendo game to a Nintendo game is a lot more simple than making an analogy about software sales from Nintendo to hardware sales from Playstation, especially when that analogy works better for well ... Nintendo hardware. Like, to make that point about Sony hardware, you have to only talk about sales from late 2016 onwards, you're cutting out the first few years of context, whereas with Switch software we're takling about their sales up until this point. Just seemed like it was a really out there redundancy, especially because you specified home consoles, to avoid a Switch comparison, which makes much more sense. But yes, your point makes sense ... just kind of oddly stated.
Then I guess we agree? Saturation > Game decline, basically.