Although the "chop a finger" tactic might be a worry in some exceptional cases... in the vast majority of cases I think "punch someone in the face until they re

Although the "chop a finger" tactic might be a worry in some exceptional cases... in the vast majority of cases I think "punch someone in the face until they reveal their password" is a more plausible tactic. It also just doesn't matter for a lot of cases. A lot of the systems people often think of as super important and secure and permanent (like banking) have a fair amount of wiggle room for rollback in the event of fraud/crime/etc, and policies/processes to minimize the extent to which you can carry out irreversible transactions. Security is imperfect, so there's value in a system which is robust to security failure.