This is a dichotomy which is laughably shallow.
A society can consensually follow a set of rules, because they believe they ought to. These rules can exist without a leader. So, you can appoint a leader to oversee civil discourse in debates about what the rules should be. You can appoint leaders to judge the interpretation of the law as it applies to real life scenario. Your leader principle applies in many situations without a clear-cut, universal leader.
The left need for a 'leader' has to do with leftism's need for everyone to "be in it together". That any decision affecting society has to effect everyone at once, and presumably equally.
This is the source of disagreement between socialists and capitalists.
And, in my mind, having "everyone in on it together" means having to have leaders, and therefore hierarchies. Within these groups, a certain few will inevitably always benefit, while others do not. I'd like to see the others try to dissent when the governing principle of society is that we all are in it totally together.
In Capitalism, there's lots of room for diversity and dissent. Not everyone will want to choose the same lifestyle, and there are resources available to accommodate differences.
Socialism fails because it's prescription for a society where "you don't have to work if you don't want to" is merely a formula of privilege for those members who garner enough influence in the "consensual" hierarchy to accommodate their lifestyle choices.
Capitalism is the most fair, because it's constraints on lifestyle are derived from material realities - which can be, and indeed seem to be optimally, improved upon by capitalist economic development. Whatever "nature" supports and you're clever enough to get away with, you can do.
Not so in a society where everyone must be in on it together.
It's not about ultimates - whether you "have" to participate in the socialist society or capitalist society, in both cases you have but little choice about whether you subsist off of roots and berries, or join the crowd. It's about organization: in socialism, outcomes are subject to central management. In capitalism, they're subject to decentralized evolution.
Anarchy can accommodate both socialist and capitalist modes. Social anarchy (Jeesuz can we start calling it this for gods sake) presumes voluntary association with groups that centrally manage resources, maybe even behavior. Market anarchy presume voluntary assent to property norms, and lets the whole thing sort it out.
As many ancaps have frequently said: we don't suggest to know the proper form of social organization, the most correct laws, or the most optimal economic norms. The social anarchists claim to have all the answers. Ancaps believe that people will try different things and settle on what works best for them. So, some people may prefer social anarchy, other locales may develop property norms.
Myself, and some ancaps, believe that the property norms will produce far better outcomes. People who don't like property norms, ideologically, will end up assenting to them eventually just because they prefer the outcomes they produce.