The problem with Stadia is that it costs money, the service costs a monthly fee, and on top of it you have to buy the games. What happens to those games if you stop paying the fee? If you stop using Stadia? If Google deprecates Stadia like many are worried. I'll tell you: you lose the game.
If I, conversely, buy the same $60 game on Steam, I know it'll be there years down the road, that I'll be able to play it on any PC I build, and I don't have to maintain a monthly fee for it.
What Google is trying has been tried many times before, by people who had more permissive game ownership structures.
Do not tell us we shouldn't be worried about using such a product from Google given their track record -- especially when the costs to them are enormous in terms of computing power and the reception has been very tepid (meaning those costs are larger per-user than they likely anticipated).