> Going back to the '90s and even the '80s it was common for, say, usenet newsreaders to have tools built in for ignoring posts from people you wanted to ignore, and the modern tools for such things are barely at that level, if they exist at all, despite the problem being even more difficult to tackle.

I was a post-September usenet user, so apparently I never saw the glory days, but what passed for flamewars back then seems pretty tame in comparison to today. And I recall having much better (plonk) tools for ignoring stuff I didn't want to see.