dickhead A then "makes a post" boo hoo poor dickhead B cannot reply to dickhead B makes a post problem solved
No, it's not "solved". It won't appear in the proper place and won't receive the visibility it should. It defeats the whole point of threading. Why can't you just admit allowing users to block other users from replying is a terrible idea, especially for a supposed "free speech" site? Even AOU knows this, which is why he "fixed" it by not having it apply to users level 30 and above.
(post is archived)