It is useful to have the word "Troll" keep the particular meaning it had originally. That is somebody who pretends to hold a position in order to provoke a response. These trolls should obviously be ignored or managed as silently as is possible. If you're struggling for why that is the case then I encourage you to read the second sentence of this comment again. The guy who abused Tom Daley was closer to the classic troll in this way. Recently, the word "troll" has found its way into popular parlance and now just means "person who says something that I don't like". This is particularly popular with the left. I have no idea why we need a special word for "someone who says something I don't agree with, or who is rude or unpleasant", seeing as this word would then apply to ANYONE from somebody's perspective (or at least anyone interesting, anyway).
The best part is that Trolling originally meant to walk round known gay areas of town looking to pick up men. So i suppose you could call any person who uses Troll for anybody is a Homophobe (even if that is a wrong word anyway)
How best to react to when on the receiving end of online abuse has been rather in the news, courtesy of some high profile recent incidents.