Because they pulled all manner of sketchy shit with RMAs and I no longer trust them as a company to do the right thing. Why buy from a company that repeatedly did shady shit to screw over their customers? That’s great that they claim they’re going to fix the problem but why trust them when they’ve already lied in the past?
It’s got better specs on paper but in practice, my Steam Deck just just about everything without issue, even new games and most games that are “unsupported” (at least as far as I’ve tried).
Some people might also like the layout better or just be fond of Asus as a company from the good old days when they were actually decent.
There are tons of reasons to hate on Nintendo, they’ve got a history of abandoning games and attacking emulators as well as game preservation.