Fewer than people think, in my opinion. Snake Pass and Outer Wilds insisted to me that they would be better with a controller and both were wrong.
Not every game will be a perfect fit, certainly, but I've had a great time with my Steam Controller playing things like XCOM, Prey (2017), and Divinity Original Sin. IIRC Civilization 5 was explicitly a part of the advertising for the controller in the first place, as a way to play mouse-heavy games from the couch.
It's not the same as a mouse but it beats the pants off of thumbstick aiming.
> Lots of PC games can be played without K+M, what's your point again?
The comment you were replying to directly answers you question about the point:
> PC games are built with power in mind that Switch does not have
The part of comment about "can be played without K+M" is entirely irrelevant to what I am saying because the preference _for_ K+M is the premise of this whole comment subtree.