Any decentralized system which is not purely trustless will be inferior than centralized trust systems. The reason of bitcoin's success is not only that it is decentralized, but also it is trustless. All these efforts like Bitsquare.io or OpenBazaar has failed to be purely trustless and relying on an arbitrator. IMHO, as soon as you bring in human interference you are no more trustless and just a flavor of centralized trusted systems.
But the arbitrator is decentralized. Anyone can become an arbitrator, all they are doing is confirming a transaction just like a mining computer would confirm a transaction.