What are the most annoying threads on CC?

Threads started by someone who joins, immediately starts a thread, and then never comes back…

Some are obviously spammers (“Buy this product!”) so it’s easy to just flag and ignore. But the ones that bother me are those who appear to have a real question, generate many replies but then the OP is nowhere to be found. I guess the discussion could still be helpful to someone (and it’s still at times entertaining as well), but I can’t help feeling somewhat annoyed (for lack of a better word).

I wonder if there should be a waiting period before you can start a thread? And/or you should have a certain number of replies before you can start your own thread. Something to show some level of “good faith” to the CC community.