Yes, also Nintendo and Switch have a restricted library. That was and is said again and again. Switch is missing for instance realistic sports games and racers, cinematic story driven games and big shooters like Battlefield/COD. And I probably forget some stuff.
But claiming for Sony the most variety without any shading also shows blind spots. In the PS5 presentation I personally missed japanese styled games (as JRPGfan you should've noticed), anything turn-based or strategy games. Hopefully they will show more later. On the other hand - and that is the point I agree with the OP - with R&C, Sackboys Adventure and Kena they showed already increased interest in widening the library. I agree R&C is not a new series, but it was a long time between releases and I don't remember that much spotlight as it got in the presentation. Sackboys adventure goes beyond earlier releases of Little Big Planet. So clearly that are great signs for more diversity in the library. And that is a good thing for gamers.
To come back around (so that you don't see it as a jab at Sony): clearly Nintendo could push into more gaming demographics, if they would focus on some of the areas they currently neglect. But I assume every company has limited resources.
And as you did draw the comparison with Nintendo: I personally have difficulties deciding which console (PS4 or Switch) has a more diverse library regarding genres. Because genres are quite fluid and most people have blind spots for some genres, that others see. That is why you see very different declarations about the diversity of libraries based on what each one sees as a genre. For instance I see turn-based strategy and turn-based RPG as something different. Others may put all turn-based stuff into one genre or even outright ignore the different gameplay and group it with RPG and strategy. So a lack of turn-based games I might see as a limitation of diversity, while others point to non-turn based games as covering these genres. And I can't really say which view is 'correct'. They are all relevant. But that is why I don't think it is possible to really answer which platform has the most diverse library.
Well it is basically a strange comparison, Sony have more variety on PS4 than Switch even if we only considered third parties, the 4000+ games have all bases covered. There isn't any genre that Switch have games that PS4 wouldn't.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"
Azzanation: "PS5 wouldn't sold out at launch without scalpers."