Here's a thought... Create a process that cleans up discussion threads that have no reported answer. The process could send an email to remind the originator of the discussion to report (1) update (2) solution. Not only will this create a stronger OTN, better technical resource for consultants hunting for solves, but it will give due points to the brilliant mind that provided the answer.
We all get busy. Not everyone thinks to invest in closing this loop. Just send a little reminder.
Make it easy on them.