Earlier quoted context omitted.
What about democracy? It is a clear rule (one person one vote) and yet it is not hierarchical.
A lot of people who advocate flat or structureless organizations actually have philosophical problems with even direct democracy for decision making. The big objection is to making majority (or even supermajority) decisions binding on the minority, which is seen as coercive. Smaller objections to things like elected positions and parliamentary procedure, which are seen as too hierarchical.
It seems to me they have a problem with anything, frankly.
Mainly I just wanted to point out that democracy is also a flat system and has no kings.
Still, majority in democracy happens ad hoc. You don't know on which side of the fence you will sit. At least, in the mean, you will agree with the majority.
(And by the way, there is a common folklore that representative democracy can protect minorities better. There are several reasons why this is untrue, and in fact, direct democracy protects minorities better than representation.)