The idea of arbitrators is what blockchain was trying to avoid. They require additional costs, time and risks. Even if one is trained, how do we make sure s_he is not motivated by a bribe that was received from one party? Smart contracts are trying to be pretty good at avoiding intermediaries but of course not everything can be solved by them. 6 eos unrefundable fee just to get the case arbitraged - that's almost nothing, but the fee grows tremendously if the disputed some is big. And there are also final arbitration costs, which is another ton of money! It's good that Oath is different in this matter, and this project sure might be an improvement in that sphere and there will probably always be people who are into suing each other to resolve matters.