I’m afraid it’s very idealistic approach :). I believe good UX should provide “less-surprise” approach and not assume and impose “people should taught first” idea.
There’s common sense - if I created something I should be able to delete it. Even in Twitter we can delete own tweets.
I understand reasoning that it’s a bad idea to wipe out topics with conversation. But I think it should be allowed at least during some adjustable timeout after creation.