According to JanH:
The word troll originally refers to someone posting a provocative message on a public forum just to hook people into angry retorts, when they themselves do not mean what they say. This last part seems to have escaped the attention of many board members who repeatly yells "troll." It has become the catch-all insult to everyone who posts opinions they do not like. The hyper-sensitivity to "trolls" is IMO a much greater threat to free exchange of ideas than the genuine trolls.
Pope