Eos white paper:
“Sometimes a smart contact behaves in an aberrant or unpredictable manner and fails to perform as intended; other times an application or account may discover an exploit that enables it to consume an unreasonable amount of resources. When such issues inevitably occur, the block producers have the power to rectify such situations.”
A centralized blockchain has no use case. It’s a much more expensive version of using the cloud. If there’s an entity that can be sued to remove something from the blockchain there’s no point to it, a normal server is always going to be faster and cheaper.