I never really got this service, you got to rent hardware but then devs and publishers could tell nvidia that I can't use my rented hardware to play my bought games?
It's a far cry better than Google or Amazon making you buy the game on their service specifically.
It's still cloud gaming. So it still sucks. But at least they're not trying to force you into a shitty locked in storefront. (Though not keeping your Steam login is definitely a pain point.)
"You have to rebuy your games, that you can't play anywhere else" isn't just "not the best way". It's straight up horseshit with no possible way to be valid. It's also the biggest reason it tanked.
The only thing about stadia that was in any way redeemable was the fact that they didn't mess around and gave full refunds for any game purchase.