For the best of my understanding, MultiChain use a central node to give permissions to the other nodes in a permissioned Blockchain. This central node is the miner of the first block.
It seems that centralization is contradictory with the principal design of blockchain (remove the single point of failure), but I think this centralization is only about given rights to to the other nodes to access the network, and not affect the distribution of how transaction and blocks are validated and added to the blockchain.
Is my understanding correct? Could you please give more insight about the subject?