Hmmm... when one person is given a designation that makes them special in some way, how is that not a hierarchy?
Central and primary would seem to be pretty much the same thing to me. Anchor a little less so, though it gives the impression of being tied to whomever is the anchor person in a way that one is not tied to other people.
I'm not sure if many people are able to wrap their brains around the idea of "separate but equal" in poly relationships, especially when they are married and feel like their spouse should be considered before all others. It seems like very few people really take an egalitarian approach to poly, no matter how much they might say they don't like hierarchies. My guess is that comes with experience.