Public Blockchain solved Byzantine Generals' Problem.
However, what did Permissioned Blockchain solve?? Can that be sovled only by blockchain??
It seems to me that, what permissioned blockchain solved can also be sovled by simple p2p network and voting consensus system without any hash algorithm.
Blockchain (Bitcoin) was invented to achieve consensus in distributed, public networks, where some participants might not be trusted to act honestly, see Bitcoin whitepaper.
Permissioned networks already have a consensus mechanism (by requiring permission to join and participate), so using a blockchain adds little or no value to the operation of the system, other than a mechanism to verify data integrity (as you've pointed out, could already be done easily before blockchain was created).
Using a chain of blocks is not the innovation, the innovation is combining it with proof-of-work to achieve consensus in a distributed, public, trustless network.