I know I'm not the only MNer to ask for this. I don't know why it isn't done.
There are topics which are a large part of MN for me, topics I wouldn't want hidden, topics I go for support and questions. And the large majority of posters are wonderful.
But there are some posters, sometimes in one thread, sometimes across a whole topic, who I find incredibly nasty, or personally offensive to me and my beliefs - and if they're within talk guidelines, there's nothing I can do, nothing to report. Their posts are deeply upsetting, or I find them goady, because they create such a reaction in me. There are long-standing, well-loved posters, who I would swear blind are trolls. There are posters who are bent on telling any OP in any topic that they ABU, far outside AIBU. And there are new trolls, who go on a spree, sometimes posting sickening stuff at night when MNHQ aren't around, that take hours to get banned. Or milder spammers selling us magic spells and filling the boards.
I know I'm probably just too invested in this site, but I can't seem to help it. I'm ready to flounce off because I can't handle my emotional reaction to the same posters, over and over. It seems such a shame to me, that I have to leave, as others have, when there's a solution that, I think, would make much of the site more peaceable for everyone.
"Hide all posts by this poster" - You don't see threads started by posters you don't like, and their posts in threads are hidden. Clicky button to unhide post. Similar to the way 'Thumbs down' comments are hidden in DISQUS comment threads, except more of a personalized blocking system. That way, you read a thread and miss the posts that are likely to upset/anger you. There are posters I would be happy to never read posts by again, and I only do because when I read a thread, I read posts, not names - only realizing who it is after the fact. I think it would have to be tied to specific names, not accounts, or the privacy of name changes could go out the window, but that would be enough.
I imagine the most extreme outcome is half of MN hiding the other half, and every thread that would otherwise be contentious just has two civil conversations going with opposite viewpoints. Imagine AIBU - half would be saying YABU and half would be saying YANBU, and both would be saying the thread is clearly unanimous!