What makes it more scalable than a database when a characteristic is a redundancy of copies beyond what would reasonably be needed for sufficient backup? What makes it anymore trustworthy than a database with only trusted actors authorized with write access?

The trustful, or verifiable aspects of a blockchain come as a side-effect of independent actors competing for a financial reward. How does one replicate that dynamic in a single organization? Why would one bother trying?

a number of benefits over a traditional database

A blockchain doesn't provide a number of benefits over a traditional database.

A database isn't even a particularly fine-grained description of a blockchain.

A blockchain is a key component of an experimental currency inspired by a particular political ideology that is at odds with many aspects of western civilization, such as the benefit of trust in a society.

It's not really useful insofar as most people can tell in any other contexts. Even it's usefulness in it's native context is not highly established.