I agree with this.
It is natural, and even a good thing, that we have differing opinions about any thread topic . As long as a person is discussing the topic, that is just conversation, or maybe even debate.
When you can only defend your position by attacking another PERSON, then you are being abusive, and trolling. It means that you have no worthwhile facts or opinions to add to the discussion, so you divert off-topic by attacking the person instead.
As far as why it is called “trolling”, I had trouble with understanding that, too; since I thought of the old fairy tale about the Three Billygoats Gruff, and the trolls under the bridge.
However, fishermen also troll for fish, and this means that they put out bait and then go slowly in the boat, dragging the bait and waiting for a fish to come along and bite.
When you think of it this way, this is actually a lot like what a forum troll does, too.