We still have the Lydd thread, since it was recognised that it was a useful topic to be debated and should (on the balance of 'public interest') remain. However, the thread starter did give a heads up that they would pull it and Danny was able to be a little sneaky and change the thread starter to himself before it happened.
Lydd thread
Unfortunately if there is no indication this might happen, then we can lose a lot of good input and debate if the thread starter doesn't like what they read, or perhaps thinks better of what they have said, and then arbitrarily removes the topic without giving anyone the chance to salvage any of it.
I don't know if there is anything on the Bulletin Board software side which can be done to prevent thread starters deleting threads without admin input, but I expect it is just something we have to live with. I'll see what I can find out.