@Nanakoko they could also do something where if you don't meet certain criteria you would get placed in a different lobby until you did. Could be steam level, profile lifetime, etc. Not very great for BRAND new steam users, but needing to have a steam profile that was 6 months old would mean that when a bot was banned, when they create a new account they would have to wait 6 months to really affect the game.

PSO2 used to have a pretty bad bot problem and more bots were being created than they could actually deal with. Once they had new areas you had to level up to get to, all the real players were spending their time there and the bots had nobody to spam. So they died off pretty quickly after that and now you never really see them.

I can't remember what game it was, some fps, but it would place you in a different match making queue if they suspected you of cheating. Basically a cheater/bot container. Could go that route too.

It's hard to make a system that won't affect normal players. The key is to try to find the best balance. I don't see a lot of new steam users hopping on TF2, so my idea could work pretty well for the majority of players.