A dish washing machine is useful. A clothes washing machine is useful. Christmas lights help celebrate a tradition that's important to billions of people, some of whom see deep religious meaning it. Cars are useful. Laptops are useful. As such, none of these things can be compared to blockchain. You're making an invalid comparison. To take one use case of blockchain, Bitcoin debuted in 2009. It's been 13 years, about half the age of the commercial Web. If blockchain was going to lead to something useful, then that would have happened already. Its failure to find a use case suggests that this is pure hype.