Blockchains propose a flawed solution to a specific problem. The issue that cryptocurrencies and friends are having at the moment is that there's a lot of other unsolved problems standing in the way of what they're trying to do, and those are difficult problems.

Which is to say, the question "Can a blockchain be used to solve [X]?" is answered "No" for almost every question.

Ah okay. What kind of flaws and what kind of unsolved problems?

Note: I am not trying to contradict you here, just looking to understand this whole thing from a different angle.