Hammers and nails
The Blockchain enthusiasts are just the latest in a very long line of groups who, having invented a hammer, think all problems are nails.
I'm sure I'm not alone in having experienced this attitude repeatedly in professional life (cue one of the last conversations with an engineering team at my former employer: "and we'll be using a new DB for this bit". Me "what, *another* DB type? That means the product has three different types of DB and multiple instances of each. Customers already think it's too complicated". Them "<shrug>" ).
Blockchain *may* be useful for low transaction rate applications where you need to guarantee zero deletion errors, but nothing else. And what happens when the code is no longer maintained and won't run on available hardware? Pity if the world had put, say, property transactions on it--.