Easy. Unlike pen and paper, the operator of an append-only database can publicly distribute it in real-time so that interested parties can read it and audit it for consistency. I don't see what the distributed consensus required by a blockchain adds on top of that, unless you're saying that all these applications require a zero-trust source of truth.
> unless you're saying that all these applications require a zero-trust source of truth.
Not all of them, of course. It's not a wonder child that aims to solve all of humanity's problems. It'll bring humanity closer, though and make it more efficient in many ways. People always try to look so narrow at it.
There are plenty of use cases and attributes (permissionlessness, immutability, zero-trust sources, etc.), and of course, not always all of these count all the time or are even desired. But it allows us to have and apply those as needed in an interoperable way.
But why do you think that its permissionless and zero-trust properties allow blockchain technology in particular to "bring humanity closer and make it more efficient in many ways", better than other technologies can? In other words, why are these properties so important that a blockchain is to an append-only DB as an append-only DB is to pen and paper, by your own analogy?