Our knowledge is constantly expanding, allowing us to build things differently than we used to. Modern cryptography, which makes things like multi-sig possible, is only a few decades old; it didn't even exist when the current banking industry was being established.
multisig exists
Cryptocurrency recapitulates the history of the modern banking system, and illustrates the necessity of regulation on a daily basis.
We only get better wheels by reinventing them.
Our knowledge is constantly expanding, allowing us to build things differently than we used to. Modern cryptography, which makes things like multi-sig possible, is only a few decades old; it didn't even exist when the current banking industry was being established.