But the hierarchy is broken by the ability of one node, err, person, to participate in multiple hierarchies at once at varying levels. This turns it into more of a graph of relationships with hierarchical elements, and while it's true you can't understand that without understanding hierarchies it is equally true that you can't understand the dynamics if you only characterize it as a hierarchy.

One way of expressing America's still-unusual social flexibility is that we have many valid social structures and it is very easy to move between them; there have even been some studies on how that works. Contrast this with the other extreme of "grow up in your home small town and never leave", for instance, where there does develop a fairly strict universal hierarchy.