Blockchains are step away from the centralized client-server model but not yet truly decentralized.
The unfortunate consequence of the success of a blockchain is that it becomes increasingly centralized.
It is too big of a burden to run a node of the specific blockchain network.
In the extreme case of Ethereum blockchain most of the decentralized apps / Dapp-s access the blockchain through few or ever a single node (infura).
It is questionable whether such apps can claim of being decentralized…