The bank, at its discretion or under order by government, can and will prevent the transfer of funds, so it's really just a case of Murphy's law.
I don't know why there has to be appeal to "fetish fantasies". Is it so hard for you to imagine a scenario where you or others might unjustly be the target of nefarious actions by public or private parties who would wield the bureaucracy of banking system against you? This isn't a hypothetical, one of things opposing counsel does in a lawsuit involving money is to attempt to freeze or restrict your accounts.
You may have never been in a situation where a bank prevents you from moving money, but it happens, and the worldview you are espousing doesn't survive first contact with such a situation.
But you don't have to take my word for it. There's a reason the market for gold ingots exists, and it isn't just to guard against inflation.