12 witnesses = centralization = not good
Your reputation here is also nonexistent so I doubt anyone cares what you think.
The future decentralization of Byteball remains to be seen. It's not pretending to be anywhere near decentralized yet.
When the witnesses are run by real-world, known identities, we can speculate as to how corruptible they are, or how likely they are to collude.
Same as Ripple.