... it only ensures that an address is certified ...
If you control which addresses are allowed and/or selectively withhold approving signatures, then you control which transactions may be processed. If you control which transactions may be processed, how can it not be said that you control the bitcoin economy? You get the set the rules because no one else can do business without making transactions. (This is not to mention all the other things which would break. Bitcoin does not use addresses internally.)
It's like, I don't know, a space station where one company controls the air. Yeah, controlling the air doesn't mean you control what goes on inside the station. But if you have the ability to turn off someone's air...