It started months ago. Though more of a de facto purge than a de jure purge, admittedly, my understanding is that it was all but impossible to say something supportive of Clinton or negative of Obama and not get your ass flooded with troll ratings.
You could say anything positive about Clinton you wanted. Some of the harsher criticism of Obama got troll rated, but usually enough people uprated in response to keep the abusers from winning. The management took away approval/disapproval rating abilities of people who did that, banned a very few "special posters," and it ceased to be a problem.
I attacked Obama left and right for weeks and never got a single troll rating.
