As a computer-illiterate senior citizen, I have never understood the term "troll."
The OP gave a definition of someone who posts "offensive" material.
I do not understand that definition.
If A says that she likes to jog, and B says that he thinks jogging is crazy, then I guess that A could find B's comment "offensive." Does that make B a troll?
I thought that a forum was a place where people can freely express their honest views (in a civil manner, of course).
If everyone has the same point of view, then what is the purpose of a forum?