How would an open operating system fix a bug caused by sloppy game developers? I don't think anyone would think "let's not optimize the (equivalent of) critical sections in our operating system so that we don't break GTA", unless you're suggesting providing 100s of different implementations of different parts of the operating system that people can choose from to run a specific game, which I don't think is viable either. Patching individual games is far easier and is actually viable, which is precisely what GOG (Good Old Games) successfully does on a significantly large scale.