In fact, you have to change marketing seriously. Byteball it is not decentralized, and never will by design.

The cause is simply: when I want to become a witness, I have to ask EVERY NETWORK NODE (controlling byteball main hub would do this easier).  
Very different is the case when I want to become a miner, I DON'T HAVE TO ASK ANYONE.
Because of that, PoW is decentralized, and Byteball not.

Byteball is a DISTRIBUTED database with twelve high reputable nodes that help network to reach consensus.

That twelve nodes FORM a single point of failure, and the power those witnesses have over the network is not related to this fact.

Don't pretend to be what you are not.