People new to blockchain and tech in general seem to think that blockchain invented the database and public key cryptography. All the ideas they propose are solved by them.
It comes back to money: a pure fiat currency like Bitcoin is only worth what its users believe it to be worth — otherwise you’ve just paid a lot for some random bits. That means that everyone who has spent real money in that space has a vested interest in getting other people to buy in. They’re not going to benefit from your use of a database or PKI and thus won’t consider those as possible solutions.
This works as well as any other system designed by the sales team.