It sounds to me like this is less about the math itself and more about the institutions that have to exist in order for that math to be useful.

Kind of like how even the magically un-counterfeitable and un-stealable cash is of limited use when the town is lawless, full of banks/vendors that are fraudulent impersonators or run by embezzlers.

You're safe from being mugged, but good luck getting your money back when you return the next day for a withdrawal/refund and the other side refuses or has fled town.