So what exactly is the problem with a reputation based arbitration market?
Because then reputation will be sold, like u see on BitcoinTalk. If u r not aware, check the Digital Goods section of this forum. Moreover, manual escrows are not a feasible solution for high trade volume.
By using proof-of-burn https://blog.openbazaar.org/proof-of-burn-and-reputation-pledges/
Can u please tell me the difference between Proof of Burn and Buying Reputation ? If reputation is bought, NOT earned, it'll also be SOLD... effectively jeopardizing the whole system. In a centralized marketplace like eBay, reputation is of highest importance to them because their reputation is not in competition within the system but outside of the system. In a de-centralized marketplace, the scenario will be different. Escrows are part of the free market supply-demand and hence reputation will itself become a commodity, leading to the formation of a reputation buying/selling system. A stable marketplace cant run like this... though I'm not sure about the black market dynamics.