Not having any middleman at all is a non-starter if buyer and seller don't know each other yet. (Note that any form of escrow service, even if "on-chain" or "tr

Not having any middleman at all is a non-starter if buyer and seller don't know each other yet. (Note that any form of escrow service, even if "on-chain" or "trustless", is a middleman, whether overt or covert.) Bootstrapping trust is a hard problem and arguably by definition requires some middlemen, some of the time.