Old school forum trolling usually just amounted to telling someone a truth they didn’t want to hear, and not apologizing for it. And I usually don’t mean like a personal attack, either, I mean like one of those statistical realities (you know which ones I’m talking about) or something like that.
Since there was an ethos of free speech then, even among leftists, it created massive drama, at the expense of whoever didn’t want to hear it. Now, and since around 2015 or so, they just ban you reflexively the instant you go off their reservation. So you can’t do old school forum trolling anymore, at least not as I understand it.