I don't know what you mean useful posts. They are pretty useful to the requester, but no use for people not requesting and not filling.
I'm happy with the way it is now. I don't know how you could implement it. Who would say the request was filled.. Not the cracker, else spammers would mark that they filled loads of requests that they didn't. No the person being supplied either. They will be too busy checking out the requested site

.. It's hard enough policing the "thank provider in thread" requirement.