I agree with this article. Proponents of blockchain tech argue its revolutionary quality is its ability to act as a decentralized and trustless database. But I don't ever hear them sort through the issue of how to agree on the schema for this trustless database. For a group of people to use a decentralized DB, they have to agree as to what to store in it, and how to store it. They need to form consensus about how the…
However, I don't think that this completely rules out their usefulness. Blockchains are more like "consensus abstractions" - if you have the underlying consensus (achieved through a governance model that can engender it), then it allows for uses like smart contracts that can efficiently work on top of it. The "trustless" property is also maintained - for example, even if a cryptocurrency is designed, issued and governed by a central bank, the fact that the network is decentralized and its integrity can be independently verified (even if it is centrally secured) still has some social benefit.