I'm literally playing nfsu 2 and signalis. I also think ray tracing is dumb af and we're nowhere near phitorealism. So no, you're dead wrong.
However, I also want to play the latest RE and Control Resonant when it comes out. Not to mention that I play these games on a 1440p 170hz screen and would like to upgrade to alienware's new ultrawide oled. Something like the steam machine would not be enough for that.
steam directly tests that hardware in steam os, so less likelihood of issues
Issues like what, exactly? Unless you have a pc that's over a decade old, you won't have any "hardware issues".
not all hardware is compatible with each other when building either
There's this thing called hwpartpicker. You should use it. Hw incompatibility isn't rocket science.