A centralized blockchain does not guarantee that at all. In fact, it's probably impossible to guarantee this for any kind of centralized service. In order to be

A centralized blockchain does not guarantee that at all. In fact, it's probably impossible to guarantee this for any kind of centralized service. In order to be able to trust centralized ledgers, clients need to keep a local copy (or a local history of hashes) so that they can detect manipulation (regardless of whether you're using a blockchain or something else to store your data).