An interesting observation by Niall Ferguson, from The Square and the Tower (2018):

Professional historians have until recently tended to ignore, or at least to downplay, the role of networks. Even today, the majority of academic historians tend to study the kinds of institution that create and preserve archives, as if those that do not leave an orderly paper trail simply do not count. My research and my experience have taught me to beware the tyranny of the archives. Often the biggest changes in history are the achievements of thinly documented, informally organized groups of people.

By the way, it only just occurred to me that “hierarchy” literally means “rule by priests,” parallel to monarchy (rule by one) or anarchy (rule by none). The Greek hiero- may be seen in such English words as hieroglyphics, hieratic, or hierophant. Presumably our sense of “hierarchy” derives from the Roman Catholic Church, whose hieroi really are organized in a top-down command structure.