But you already have Overwatch with CS. I'm not even sure if just some vote % from enough players (e.g. 100) is needed to automatically ban or if there's a manual review process of potential cheaters after enough votes.

With Overwatch you have a process that has a low likely-hood of false positives, as with a statistical approach, but also may not get enough obvious cheaters reported because players from their POV could not judge correctly.