I'm not sure that's exactly the right read in a way that is important here. Sure, if you buy a game on Steam or EGS, you're still kinda just "renting" it since if they go away, you can't play the game because of DRM. That said, I have a lot more faith that Valve will be able to keep offering Steam, since it's so lightweight, relative to the clear amount of cost inherent in running Stadia.

It's a lot harder to build a walled garden from scratch as a late-comer, and even harder when you're building it in a swamp where people are less confident about moving in.