Banks can potentially act as gateways that prevent large transactions that are otherwise possible with crypto. They can do this simply by saying that for any amount above a certain level, you need to attend in person.

The whole "time immemorial" argument is a little silly when we put it in the context of modernity: we have safeguards people didn't have "before money was invented" because we're the beneficiaries of a sophisticated set of social rules intended to protect people. Getting rid of those safeguards because they're recent is fairly likely to make our lives worse.