It feels like particularly in finance, that startups who disrupt traditional players do so without a full understanding of all the corner cases and none of the regulatory accountability which is why those traditional finance players were so expensive in the first place.
Not even corner cases. I worked for a fintech that launched a dda-ish product that had 16 digit account numbers, issued sequentially, with no check digits. At launch there didn't seem to be a CS process for dealing with pretty obvious "customer mistyped account number and sent their money to some else's account." problem.
Feature parity with blockchains.