I wonder how much of this issue is aggravated by the fact that we are unable to identify children on the internet. In regular society, we would not dream of putting up with anti-social behaviour of this type but online we seem only too fight for their right to do this, with what seem to be rather drastic consequences.
I think these behaviors are extremely innocent compared to some anti-social people we put up with in regular society. Any important soccer match around here involves way more destructive behavior than this.