This is the main reason why I stay away from most OU battles. I do play them occasionally (As in the tourney here), but espically in that tier, I personally see a good amount of people bashing other players.
I'm not saying that everyone does it, or that the other tiers do not have people who act that way either. They do. But that is how most people who play games competitevly, not just in this series. It is sad that it happens, but you just got to deal with it and move on.