You can't see any benefit to never having to download a game before playing it or running 4K games without needing the latest gaming hardware? Given the obvious theoretical benefits regardless of how Google actually delivers on them, it's hard not to take your claim of "no actual benefit" as disingenuous.
I should have said "no benefit to me"
The benefits you cite are not things that matter to me at all. They may matter to others, of course, but I can't speak for others.
I'm a very casual gamer and have no particular opinion about Stadia in its current form. And am perfectly willing to believe that it's pre-1.0 in its current form. But it's the direction things are headed.
I'm not a hardcore gamer -- I think hardcore gamers would call me a "casual gamer". But Stadia is not interesting to me at all. It offers tons of important limitations, and brings no actual benefit that I can see.