What is a selfmoderating thread? Is it what poster Sig said: "It's just the person's post in the thread that gets collapsed, the thread remains the same" ? Sig sounds like a sharp cookie in his posts and I have a hunch he is keeping all his good trading knowledge under his hat.
No. I guess it depends on the software used by the site owner. At T2W, when one opens up a journal, he can "pre-block" those who are on his Ignore list, whether they are on his list when he sets up the journal or he adds them later when they begin disrupting the journal. They are then prevented from posting, and one doesn't have to deal with the quoted "ignored" post which then generates even more off-topic posts. The blocked individual gets a message along the lines of "you are blocked from posting to this thread; contact the OP for permission to post". Or the OP can limit the participation to those on his "Contacts" list, which I suppose would be comparable to ET's "People You Follow" list. The latter results in what amounts to a "private" thread that everybody can see, and those who want to participate in the thread can PM the OP and as to be put on his Contacts list (I see little point in ET's private threads since no one but the participants know the threads exist). Hope I understood your question.
I'm only uncivilized in the politics section and to dumb posts elsewhere.... But quality posters are not making dumb posts so feel it's a good compromise.