The escrow used to be a trusted third party though. Blockchain moves the "quantity of trust previously assigned to the escrow agent" to the two parties. If one party disputes for some reason the algorithm this can't be settled automatically. With a trusted human escrow agent, an abnormal situation would probably end with him sharing part of the blame , which help resolve the conflict in a way that is not fair, but surely blame-able. There is nobody to blame with a machine though.