Enablers of abuse in online communities

In a lot of conflicts within online communities I've seen, I've noticed a certain pattern of behaviour emerge. To talk about this, let's first distinguish three groups of people that can commonly be found in conflicts: The troublemakers. The trolls, the assholes, the abusers, the bigots. The enablers. Friends of the trouble makers, people who silently hold the same beliefs (or less silently but…