Why your blockchain app likely won't work: The cost of a byte of data on the only blockchain that is immutable, Bitcoin, is ~8.5c, around 1billion x cost on a hard disk. Other than a ledger for a politically neutral global monetary system, nothing is worth that kind of cost
There's also development time. I suspect there is a class of apps that need relatively little storage but high resilience where it makes sense. Basically paying the miners rather than some additional dev and/or devops salaries.