It's an interesting idea.. but it seems like it's centralised on a single website, which is a single point of failure (and vulnerable to things like DMCA takedown notice).
It does not have to be this way. Payment processing and dispute arbitration can be done by different entities. Payer and payee agree on terms of payment, choose an arbiter and instruct payment processor that in case of a dispute arbiter will have a final word on whether payment needs to be reversed or not.
This is basically the same as a chargeback, except in case of a chargebacks payment processor and arbiter are always the same and you cannot opt-out.