No its not just the user though I get your point regardless. The point I'm making is that 4K is not really 4K more often than not. Sure you have the pixel count, but if the input is of lower quality, what's the point? Not every pixel contains 'detail'.
Take simple video online: you always get a compressed stream
especially at 4K. Gaming, similarly: things like temporal AA are often forced on you, variable rate shading, lighting quality, etc. Another factor you can't control is textures. They come in a set quality / qualities. Another one you can't / can rarely control, is LoD; geometry and number of objects on screen.
There is a point at which developers really don't want more information on screen before it hurts overall playability, and every res above 1080p struggles with that. Sure you can make everything super detailed, but is it still pleasant to look at? There is a balance to be struck.
Its not about what you get, its about what's useful, usable, and how it trades off against other drawbacks. Higher res is lower battery life, more power required, bigger GPU for the same FPS, etc.
Anything over 300 ppi on a phone is utter bullshit. Yes you 'get more'. That's because the market is saturated and every company desperately fights over every number to have the bigger sale epeen. Useful innovation is not in smartphones anymore for half or nearly a full decade. The only reason phones need somewhat higher PPI is because you're obviously killing your neck a lot more than you do behind a desk
But the higher that PPI, the more you will have a tendency to crawl in your screen to get all that detail resolved. So even ergonomy takes a hit with PPI overkill.
It kind of echoes in this thread I think, and in the poll results. 1440p is dominant, 1080p lagging, and on Steam with a less enthusiast userbase, its even still 1080p dominance. In both environments only a niche 'wants' 4K, and of course in this forum higher res is overrepresented.
15.6" 3840x2160 OLED 
