Here is an example.
Say a poster posted something. Then another poster posted "Only uneducated idiots and fools believe that" That's basically saying that the OP is an uneducated idiot and fool, as are anyone else sharing his opinion.
That could be classed as bullying, or being mean. Whether the poster uses that tactic to stress his point, or intimidate, or as he/she can't deal with being disagreed with is unknown. But it turns a discussion into an insult fest. Some retort back. Some remove themselves from the discussion, which is a loss. I will freely admit that I have been ticked off for retorting back. On that occasion I didn't call a spade a spade, but I implied it, and got ticked off, which I accept.