In an effort to avoid a nitpick war, I just can't help but think what I'm thinking of isn't your definition of hierarchy. I'm not talking about an exploitative dynamic, but one of agreeable parties submitting to authority in any given setting. An apprenticeship with a master, a spousal dynamic, a defense collective with a commander could be some examples. It doesn't align for such a relationship to be rigid if consent can be revoked at anytime. I tend to find humans naturally agreeing to such arrangements, whereas coerced hierarchies should be dismantled as a principle. Looking up voluntaryism, it seems to carry alot of other connotations besides what were talking about.