What's your definition of a "regular" database? If you need a distributed, well-sequenced, auditable trail of cryptographically signed operations representing the transfer of value, that quite literally can be fit to match the definition of a blockchain.

People who haven't done it probably underestimate the incredible amount of fiddly nonsense is involved in actually writing accounting software to handle a ledger.

Banks and brokerages very often use software written 40 years ago because it's so much trouble to get correct.