Why do we need to chain the blocks (creating blockchain) in a permissioned blockchain?

Question

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.

Answer 1

I think you might already know the answer, based on your question. The "chain of blocks" has value in Bitcoin because of the proof of work. It is also provides a data structure that can be used in an efficient way to verify the integrity of the chain, but that is not really what makes it interesting.

A permissioned blockchain, obviously, requires permission to join, so a proof of work isn't really necessary. If someone misbehaves, they can be removed by whatever process prevents the whole world from joining. The proof of work provides a consensus mechanism in a distributed permission-less network.

Another problem is the word "blockchain" is very over-hyped term that has different meanings in different contexts. The reason why the "chain of blocks" or "proof of work chain" Bitcoin Whitepaper is interesting is that it solves the problem of distributed consensus. Any other definition isn't nearly as interesting.

Based on that, it appears that many companies are trying to figure out how to make a profit on the "blockchain" hype and one way is by creating their own coin. Unfortunately companies are used to controlling their products and that is why you see premines and closed blockchains because that is how companies have traditionally made money. I look forward to more solutions where companies provide solutions on top of the existing infrastructure (e.g. like building web apps on the existing internet) rather than trying to control it.