1. You can't trust any single known party, or group of parties, to attest the integrity of the ledger (otherwise, you could just use plain old digital signatures)
2. You need infinite pseudonymous accounts in this ledger.
3. You need it so badly that you're willing to forgo a significant share of whatever value having this ledger creates, regularly, forever (mining fees).
There have been attempts to rebrand blockchain as anything containing a chain of digital signatures, no mining needed. In which case it's old technology - but in that case I also agree that it has a use.
Artists are by their nature known parties, as are factors in a supply chain. They may have a use for digital signatures, but they have no use for a scheme including mining.
1. That currency is going to be heavily speculated because it's unregulated by design.
2. That currency is going to be used to bypass regulations that do in fact protect people.
3. That currency will be used to bypass an international system that is designed to allow nations to punish other bad national actors without resorting to war.
If you want to foster anarchy and to create an expectation that any individual is on their own and are actually prevented from getting assistance when they lose everything then a cryptocurrency is an ideal ideological fit. If you want something more balanced then merkle trees might be a useful tool but leave the currency aspect out of it.
What's your definition of good? An immutable ledger is a good idea and useful. An immutable ledger where every write costs 50-200 USD isn't as useful, for example.
Any application where you need an immutable ledger is a good application for blockchain. Just because crypto enthuisiasts are trying to shoe horn this technology into anything and everything doesn't mean the above isn't true.