I think they already do this with their matchmaking system. I'm a bit out of the loop on Valve's newer games but at least with the older ones, if you were chea

I think they already do this with their matchmaking system. I'm a bit out of the loop on Valve's newer games but at least with the older ones, if you were cheat banned you could still play but were just stuck playing on the servers without cheat protection (so basically cheaters got stuck playing with cheaters).