I don't know. I mean placong a middle man through all this just makes decentralization pointless. If the problen is conflict resolution then I'd guess we can have a sort of judiciary system , which is supposedly the SEC. This entity shouldn't have a hand over crypto currency at all. It just makes them unbiased and all that.
I believe SEC is not a kind of judiciary system but it is kind of regulatory authority for investors and investment-instruments and its providers. Definitely SEC will not handle basic transactions related disputes. I agree with you that a middleman entity should not have any influence into crypto space. Yes, a middleman authority must have limited power like controlling to only the transaction related things not into the entire system.
We always must need some judiciary system and dispute governing system so that the transaction related disputes will find its solution. When no one will be controlling both the parties(buyer and seller) then the chances of scams will be highly and also no one will be ready to initiate the transaction progress at first.