multi-sig addresses one aspect of the problem but not everything. The underlying problem is that the system is brittle rather than robust, and multisig only helps with a specific challenge (“I don’t want a single key loss to lose everything, but don’t want to make copies of the same key”). It doesn’t help with many common scenarios: “I was compromised”, “my employee abused access to my keys”, “someone made a typo in a transfer”, “I am choosing not to comply with a court order”, “our CFO died unexpectedly”, etc.

Contrast this with how easily this could have been resolved in the financial systems which are actually used and you get an immediate appreciation of how valuable it is to have a way to handle human error in systems used by humans.