Yeah, but why it would be inefficient?
Entry cost is negligible and the need of open thread is very visible.
I would rather say that there's no market because there's no demand: nobody cares that much about gaining that karma. Or maybe it's not a high status activity.

Maybe I've taboo'd non-MrMind's from doing instead and legitimised a kind of proprietary right to it to you!

Perverse incentives are everywhere! ;)