The problem is not that the OS can’t attest the app is secure. The problem with cheating is that the game servers cannot attest the client is genuine in all aspects that matter: non-modified client, running in an environment where there is no inspection of its memory for map hacks, aim bots, and more. The only way to do that is a remote attestation of the entire chain: hardware, locked down OS, app. (If the OS isn’t locked down it can’t prevent the player from running cheating software.)

The choice is simple: tolerate some level of online cheating, or require remote attestation to run the game. If you ask me, I’d rather take the first option. Locked down game console already make me a bit queasy. A locked down desktop, laptop, or palmtop? That’s not acceptable. People should be able to run any program they want on their computers. If that means the end of online gaming, so be it.