In the case of a small startup, a "flat" structure is sometimes simply a description of what the group have worked out in order to be productive and effective. In cases where I've seen firsthand a fairly hierarchical management structure, decisions were often carried out in an abstract, awkward a manner that was in many cases not in the best interests of the company.
I've seen it done many ways. My intention with this essay was not to create a comprehensive reading on the subject but instead to communicate about what I've learned thus far (from experience, observation, reading, etc).
I had hoped to come across in favor of a flat style with the admission that there are times when direct authority is the best solution to a startup's problems. How'd I do?