Massive institutions with billions of dollars at stake would rather have a predictable and stable regulatory regime to conduct transactions in the shadow of then to rely on a technical solution that supposedly obviates the need for one. Things come up -- bugs, acts of god, internal fraud, hacking, flash crashes, and so forth and so on. They want to be able to go to arbitrator and ask for a sensible and reasonable result and not be reliant on a totally inflexible mechanical rule set. Not the least of which because they can afford the very best lawyers to try to convince those arbitrators that what they want is sensible and reasonable.