It used to be the case that "flame" was a word people knew, and that flamewars were treated as flamewars. Team "not getting involved" would peel off from the conversation and warn people with positions at stake not to get involved - there was no productive disagreement to be had in a flamewar. The people who couldn't stay away _knew_ they were in a flamewar. Everyone else knew to just let it run it's course. Nobody's opinion who mattered would be dumb enough to be swayed, so we just ignored the flamewar until it burned out.
Unrelated: In same time period, a lot of websites have popped up with content and editorial direction that profit off of the fact people get trapped in perpetual flamewars; maintaining/replenishing their audience by pouring fuel onto the fire. I'm sure this is a coincidence.