A lot of it has to do with the tools games give you to deal with it. If they know you can't do anything about it, they'll be as toxic as possible.

Games with FF tend to self-regulate much better. The other night I was playing pavlov TTT and a guy yelled "Everyone, if you hate removeds, switch to the nazi skin" during the pre-round, and the rest of the server immediately banded together to hunt them down.