Why don't more sellers/buyers use PlayerUp for MM services?

Don't know if this is against the rules to post a link, but Middleman: Sellers Guide | PlayerUp Accounts Marketplace. Player 2 Player Secure Platform. is a super secure service that is perfect for buying and selling tags/accounts. I know some Sythe users offer MM services, which is great, but PlayerUp is very reasonably priced IMO (like seriously cheap) and has a great policy that serves every party involved. Don't trust anyone who won't go through a MM. Thoughts?