I have a suggestion to make MG safer for buyers:
Make the user rating/likes dependent solely on the reception of module(s). Or at least bias the voting system to favour positive feedback for good sellers, and neutral for buyers.
A scammer might be a good buyer, never (obviously) a good seller. Thus, if users also rate for good buyer this drowns out the good seller factor.
I was scammed last year (seller has since changed name and I eventually lost track). He had a few good likes when I decided to buy from him. When I started to suspect a scam (already too late) I reached out to the users who had given him the likes. All of those likes were from people who had sold him modules, no buyers.
A buyer pays in advance and can't scam a seller (except for some fantastically elaborate ploy), a seller can always scam a buyer. So it makes sense that ratings should reveal how good a seller and not how good a buyer or buyer/seller together.