The use case is money. That's it. All valid use cases involve a transfer of stored value. (eg. money, securities, collectable stuff)

For everything else there's a much cheaper option, even for time stamping. Anything involving "proving" something, meaning making some assertion at some time is not a good case. For those look at certificate transparency for a better example of how to handle that. When people say "storage", I say no. All valid cases which involve that are really about the handling of payment for storage, not the storage itself.