Moba games always have beyond awful communities, I dont know what it is about that genre but if you play it seriously you more than likely are a prick, if you're not you're in a very small minority....but on the same note when kids chain die and feed other people and you lose because some kid is being a mongoloid..I can kinda understand why kids are like that. However I do not critique kids and go "OMG YOU SERIOUSLY BOUGHT THAT?!?!?!" and such, thats a little too elitist for me. The only bad thing about these style of games is if someone is ultra annoying you can't really mute them or you risk not being able to coordinate stuff.
But to sum up my mini-rant, DoTA, LoL, HoN, whatever other knockoffs all have beyond awful communities, its just the nature of the game. Much like how if you play CoD you will be called mean words by 12 year old British children.