Well, we are talking about blockchain here and I am just pointing out that blockchain is not only decentralized but rather, can be centralized. As of the question, if we need a centralized blockchain, I think the same thought will be given to the decentralized blockchain system. Each has its pros and cons. We cannot say that decentralized blockchain has no cons, the same goes for the centralized system.
The problem with us is that we became fanatic of something that anything against what we believe becomes wrong. We fall into the category of being biased and that is not healthy.
I was just curious to know if I understand the blockchain technology correctly. That is the beauty of new technologies - we learn something new about it every single day. So, in my opinion, the only realization of blockchain that really works was firstly introduced in bitcoin network. We all know that this kind of blockchain is a great solution to the problem of digital cash, we don't need a central server to verify our transactions anymore. Transactions is part of history as long as they're written on blockchain. It is immutability of blockchain, which can be considered one of the main features of this technology, makes it unique. Before invention of bitcoin, we have never been able to achieve immutability. It is not possible to provide immutability in centralized blockchains, so they can use data bases or spreadsheets instead, it is cheaper and has the same effect.