If regular law is the ultimate arbiter of the correct location of funds in this system, then we don't need this complex network of energy-hungry computers constantly double-checking each others' work to make a financial system. We can just use regular computers, like before.
Isn't it a consequence? If the entire foundation of your system is irreversibility and finality, then doesn't it effective becomes true? (unless you are big enough to force a network-wide rollback...).
But that's exactly what the decentralized crowd is arguing. You encode transactions and no centralized authority (e.g. a country's judicial system backed by people with guns) can override it. A natural consequence is that no one can override a mistake either.
Legal contracts in the physical world can be poorly drafted as well. But courts don't usually allow ludicrous results arising from honest mistakes.