If you need someone else's permission to use it, then that person is both a bottleneck and a source of control with power that is likely to be abused. It is really important that these systems be "permissionless" in order to be legitimately decentralized. (Though I wonder if you ask that because you think the term means something to do with data control. It doesn't.)
I know exactly what "permissionless" means in this sense. However, given the only way that a transaction is materialized in the blockchain is for a block to be mined by someone, that sounds like a bottleneck to me. A pretty bad one if Proof of Work is being used!
