The good thing is that the ignored person cannot (if things have not changed), post in a thread you started. I think this can make us feel safer because even if they can post in the same thread we do (even if we just see their name), they can't post in a thread we started which might be a more sensitive thing.

Also they can PM you but you don't get the PM. Although, if you one day decide like I did that I had too many on ignore and instead of taking them off one by one, I took all off to add a few back, in that space, PM's that could not be delivered to me were, several months after they were sent. So I guess blocked PM's live invisible endlessly. LOL.