LeninGrad, I agree that a "hide poster" feature (or whatever it might be called - on another discussion board I sometimes visit, it's called "blocking,") could make an enormous difference. Yes, it is of course possible to ignore and not respond to posts that you don't want to respond to - whether because you just don't have anything you want to say, or because you believe they are being deliberately provocative and do not merit a response. However, it can be irritating when someone effectively "spams" a discussion, insisting repeatedly that they get a response. Also, others who haven't read back far enough or may not be aware of the history and context may be puzzled as to why one person is being ignored.
Hiding/Blocking means that you can simply choose not to see contributions from specific people, for whatever reason you choose. The other person can still see your contributions (usually) but you won't see anything they write. That's generally good and can save quite alot of hair pulling. If you appear to be ignoring someone, others will guess that you've blocked them. However, it can disrupt the "flow" of a conversation, particularly if other people are engaging with that person and you are only seeing part of the discussion. But, taking yourself outside a discussion like that is sometimes worth it because you don't get dragged into side discussions that are usually designed just to derail and cause arguments.
Eventually, quite a few people will block/hide a contributor who seems intent only on generating disruption and getting attention, so it's actually possible to have a discussion without fending off attacks at every turn.
Does that mean that some people will get "hounded off" the message boards? They'll probably insist that they are (but hey, some shout that now just because they find most folks in a given discussion refuse to agree to change their minds to reflect their views.)
No one here is obliged to listen to anyone else, let alone obliged to agree with them. Blocking/hiding just provides a useful way to make it easier to ignore those we might choose to ignore.