It’s easier to roughly copy, sure. As you say, examples of that exist. But outright cloning a game with only streaming/realtime content available? No decompilations, 3D asset parsing, or ability to run lots of simultaneous game loops? That would take ages and/or break the bank.

I’m not saying AIs are technically incapable of doing this. Rather, I’m saying that Stadia-as-DRM makes the act of copying technically infeasible (costly, slow).