> I'm not sure what this has to do with fiat currency.

Just read their reply as "traditional payment methods". Nothing really protects credit/debit card transactions, the security of which is basically the emperor isn't wearing clothes.

I'd even say the security to directly access my bank via customer support relies on obvious, basically public, identifiers that to me seem somewhat trivial for a potential attacker to socially engineer.

… parent's "solution" does strike me a bit like "meet the new boss, same as the old boss", though.