Well i think suggestion has been put foward in the past! Basically I dont think aSD wants to run the risk that pirated games etc will be sold through it!
you can have a mod to monitor the forum to see if anyone sellin illegal backups. thats what they do over at other sites. hey i volunteer to be that person if you want.
Not just that, if there's a mod, there's a sense of "personal gurantee" on the products that "get through" the Moderation and if someone gets screwed .... ya
not to mention a mod cant see what goes on in PM's, it would really open up a nasty can of worms. good thing there's ebay for that stuff. we stay out of the auction/buy/sell/trade business, and they stay out of the forum business. it works out really well