As one of the earlier active members of this forum this has always been something very clear to me. I was the first (and only) reliable Steam game seller here for some time. I made it a point to help get people started and single handedly drew in hundreds of users from outside the forum to it.
New users are required to take risks to start out, it is just part of how it works. People who are known to be well trusted can and should serve as gateways into the forum and its systems of exchange. People who are trying to abuse this as I stated earlier make themselves obvious fairly quickly to any one taking the time to do at least 30 seconds of due diligence reviewing trust ratings. New users get a trusted start into the system, and the forum gets another contributing member instead of just a lurker. The benefit outweighs the risk in my opinion.