I don't think it's realistic to believe that hierarchies wouldn't emerge one way or another. The hierarchy can arise in the form of a mafia, or in a more regulated way.
If you have an example of a mafia formed in a stable area without inequality or hierarchies I'd be pretty interested. People in general like the path of least resistance and only turn "violent" when they feel they have to.
However, if your view is most people are just bad and will do bad things on their own then sure, perhaps you want hierarchies in place but I have no clue why someone would think the bad/selfish people wouldn't just rise to the top and just become worse.
I believe that most people are good, but there are also some people who are evil/psychopaths, and I don't see why they wouldn't organize a tyrannical hierarchy, they could use violence and other means to rise, I see it as a risk.
The problem isn't so much that hierarchies just arise naturally, the problem is more that these societies aren't very long lived because they're pretty useless at defending themselves with violence.
It's not totally uncommon to find an anti-hierarchical company. It is almost impossible to find an effective anti-hierarchical military.