You are correct Gold, however, I don't think anyone on theory11's staff would want to sit and go through all of the transactions, complaints, ratings, etc. They don't have the time to do that and keep up with "our" demands of releasing new effects, decks, and such.
I understand that the voting / rating / feedback system would rest on the shoulders of the seller and on the buyer as well. Ebay has to fight battles all of the time about bad transactions and negative feedback that then in turn hurts the seller. I just don't think it is something conducive to the community and would require additional support efforts from the team.
Don't get me wrong...I'm sure we all have TONS of crap we would like to unload, swap, sell, buy, trade, but to make it full proof and work efficiently and effectively would take a lot of moderation and work. I would hate to have the complaints then filter onto the boards where bashing would then take place.
If Theory11 does decide to do this, perhaps it could be a TRIAL basis to see how transactions would go and then if "crap hits the fan" so to speak and things get ugly..well..then that feature / page gets deleted from the community.
This is just my opinion fellas, feel free to disagree with me and my feelings will not be hurt. Everyone may speak their piece. The floor is open.