Having a single sub-forum for it, means we'd still have to look at them all and they would still fill that whole sub-forum. It's just adding an extra forum we'd have to keep checking.
Having a single thread for them, means names would get lost and confused with all the different accounts, and things will get confusing with who's talking about which multi-account. This is the reason that in "Do you have multiple accounts?" when we conclude someone has a multi-account, we make a new thread about them anyways for their ban. So they then can explain if they want, and others can input any more multi's from them, etc. If people tried to explain themselves in one big thread, it would grow off topic very quickly.
Just keeping them in the Cheaters section that's already in place keeps it organized and the most manageable.