I could see a model where someone joins and is given 500 topic bucks, to post you spend your virtual moolah. If its poor quality it is money lost, eventually you run out and no more posting until payday - your budget is spent.
If you post valuable content you earn more moolah so you can carry on and grow your presence.
If you are flagged you are fined.
With spare moolah you can buy badges and virtual merch and increase your status.
I could get behind a model like that. Doubt it would go down with the current human psyche but as a system for driving behaviour it would be an interesting experiment.