Then why do companies with flat hierarchies exist and operate just fine? You don't need someone at the top because you don't need a top.
See:
* http://mariewiere.com/2012/03/04/a-company-that-manages-with...
* http://agile-commentary.blogspot.co.uk/2009/09/bees-self-org...
The interesting thing about people, and any social, intelligent agents is that they self-organize.
Even bees (intelligent, social agents) do this:
http://www.pnas.org/content/96/22/12611.full
So do ants:
http://en.wikipedia.org/wiki/Patterns_of_self-organization_i...
We can even manage traffic without direction:
http://thecityfix.com/blog/naked-streets-without-traffic-lig...
The biggest myths of our societies are that we need a hierarchy, directions and managers. We're quite capable of leading ourselves and getting everything done. And more efficiently, no less.