I think to some extent. But it has more to do with DPoS protocol. You must understand that a consensus mechanism is sometimes at the cost of decentralization to giving it an edge on scalability. With DPoS you can really improve scalability but to some extent at the const of decentralization.
The voting procedure to choose the main 20 observer is again key to check whether it is getting centralized or not. Someone told me few weeks ago that without the voting from @freedom account and any steemit inc account, it is almost impossible to feature in top 20. If that is true, then you can indirectly say that it is centralized.
There must be a long debate over this and many people here in this platform have a sense of the same thing which you have asked here and with a proper communication with Ned, top 20 observers and other knowledgeable person in this platform and the common public etc the real basis can be established and understood.