Well base operating system or hardware driver. There are exceptions, the pps driver for timekeeping makes sense to be kernel level too.
But games developers? No, they have no right to ring 0. I understand they want to protect from cheats, but they're just moving the battleground to a part of the system that results in blue screens/panics when it fails. And cheat developers will follow them there and even move to the hypervisor if needed, trust me on that.