mobas have a reputation for having some of the worst gaming communities you can find.
LoL's tribunal really helped. It used to be much worst than it is now.
Of course, no one can ever get rid of jerks completely according to the notion of John Gabriel's Greater Internet Fuckwad Theory.
Although, personally, I do despise when people keep dying in the early game... why can't you hug your turret, it'll love you back.