The main question is:
What does "chaining block" mean in a permissioned blockchain? OR in any blockchain network in which creating a new block does NOT need consuming resources/energy ? (even in the case of proof-of-stake)
Does "chaining blocks" (creating blockchain) WITHOUT consuming resources (in the case of PoW, this resource is electricity) make sense? where, re-calculating all hash values does NOT have any considerable cost and it takes few seconds.
In other words, Why do we need to chain the blocks (creating blockchain) in a permissioned blockchain network (such as Hyperledger whose consensus mechanism is PBFT)?
What does really mean chaining blocks without consuming resource/energy? where re-calculating all hash values and as a result replacing all blocks can be done EASILY and RAPIDLY.
The thing can make transactions history immutable in Bitcoin, is a PoW with enough difficulty and not only using blockchain data structure. Otherwise, only chaining blocks based on ex. a PBFT consensus (or even based on proof-of-stake) can be interpreted as a fallacy.
What is the role of blockchain (chained blocks) in a permissioned network? where if one is able to change one block, then he could change the whole of chain as well, by re-calculating all previous hash values, since there is NO difficulty to calculate hashes.
Note: I tried to bring up my question in several different forms to be more clear. In the case, you think some additional explanation is needed, please let me know.