> I don't think there is much if any distinction between what Stadia is able to do and what all the other game companies are able to do.

Stadia is able to make a game completely change and/or disappear whereas other game companies that put the game executable and data on your computer (either by some automated method like Steam or by you manually downloading it like GOG/Humble Store/GamersGate/etc) cannot do that because you can copy the files and preserve the game. Even if you specifically cannot do it, someone else will do it.

As i mentioned above, see Konami and P.T. for an example.