The aim of Wikipedia is to create a free encyclopedia with valid info in many of the world's languages. Having so many editors is a strong and also a weak point but surely is not centralisation. Not in the sense that some central authority is giving an ideological direction. The authority for example is exerted by administrators to stop/diminish neverending wars of words between editors with different opinions.

The way Wikipedia functions is much more complex (a good read for many) but at least for now I can't see nothing evil as you implied in your post. On the contrary...