As opposed to blockchain where reversal depends on the grace of the merchant.

I've often wondered whether payments providers entering the blockchain space (like Visa/Mastercard) would act as trusted intermediaries for dispute resolution. Kind of a 2-of-3 multisig to disperse the funds in escrow.

One of the most common examples of smart contacts is a reversible transaction with dispute resolution by a third-party.

Infact you could implement exactly what you suggest in a similar way.