In TerminusDB we have built an immutable DB based on these (our storage implemented in Rust ) principles and are now moving towards content addressable hashing and encrypted layers ; however, our user community haven't really found many use cases for these features. I'm sure financial services and other such heavily regulated industries need the governance and confidence, but don't have any detail of the likely implementations.
This is the exact issue that currency-based Blockchain systems avoid, at great cost - the essential requirement for a centralized third party to resolve all disputes
The article didn't address that threat. One defense would be to make the entire hash chain available, and let a third party verify that it hasn't changed. Of course you could also replicate the entire database to the third party, so you're just gaining some efficiency and privacy (which might be worthwhile in some cases).
A blockchain on the other hand makes data really immutable. You can't change the data without doing an enormous amount of work, or (more recently) losing a large amount of staked currency.
The only alternative to a blockchain is to publish the latest hash widely in a verifiable place such as in a well-known newspaper.