This really doesn’t happen that much. When it does, it’s usually because the poster was a sock or troll or a spammer. As for why we don’t make announcements of those kinds of bans:
If you have a question about a thread or poster who “disappeared,” please DO NOT post an inquiry. In probably 95% of such cases, the thread (or poster) that vanished was an attention-seeker – a spammer , sock, or troll. They’re out for any attention, even negative attention, and we don’t want to give it to them. They disappear, as do their posts. And as do posts about them.
So, if you have a question about such, please email a moderator. DO NOT post your question. DO NOT give these folks any publicity, acknowledgement, or recognition.
If you try to get such a thread via a link, you may get an error message that says something like:
That probably means that the post or thread you’re looking for has been deliberately “disappeared.” Email a moderator if you wnat more information in a specific situation.