I think it is less about what you can do and more about what it prevents. Blockchains are really an example of triple entry accounting. A transaction is local

I think it is less about what you can do and more about what it prevents. Blockchains are really an example of triple entry accounting. A transaction is local to you, local to the party you deal with, and public and (more or less) immutable to the public. If we used, for instance, a government-run blockchain to record all business transactions making "cooking the books" much less possible (no Enron). So it is useful for no fraud payments (guaranteed payment) and no trickery transaction/accounting, which is literally all blockchains are when you get down to it. The downside is that the transactions are all public knowledge to anyone contributing transactions. But it could immediately be used to track government spending (yeah right) or non-profit spending which should both be more or less open books.