Kickstarter and PayPal surely have large teams working on arbitration, review and fraud that could be delegated back to the involved parties vote with some rules.
And law suits can be very inefficient.
This absolutely could be solved without a block chain.
How can code on a blockchain decide whether an eBay listing was fraudulent without paying humans to make the determination? Unless you have a general AI up your sleeve!
I don't understand how arbitration would work. Say "A" buys something from "B". Later "A" complains what was shipped isn't what he ordered. How do you solve this with a blockchain and votes?
Bookies have been doing it forever with questionable effectiveness.
PayPal offers arbitration on stranger to stranger sales. Again with questionable fairness in tough cases.
Kickstarter et al are doing a pretty good job as arbitrators and collecting money and issuing refunds more or less fairly.