hmmm I keep wondering how you came to the conclusion that capitalism comes with hierarchical structures attached to it. Would you mind to elaborate, please?
Don't have the time to elaborate now, I already tried to explain it thoroughly in the many pages of this thread: https://bitcointalksearch.org/topic/libertarian-my-ass-160726
The very simple answer is that in a capitalist system a vast portion of the population is dependent for its living upon the selling of their labour, which results in wage slavery and private hierarchy. Anarchism is a vital philosophy that not only touches politics but also economics, in the Rothbardian interpretation the "no-ruler" characteristic of anarchism is only relevant for "government rulers", while the "private ruler" is acceptable (e.g.: your "boss", the one telling you what to do in order for you to be able to survive thanks to the wage he is paying you). For a classic anarchist no ruler is acceptable, private or public.
TL;DR -> in a capitalist society, the wealthier de facto rules, thus the "no-ruler" principle is impossible. It can be argued that a very primitive form of "anarcho-capitalism" already took place in the middle ages, and those where hierarchic societies (in fact many Rothbardian followers present the Medieval Iceland society as an example of anarcho-capitalism. They like this example because Medieval Iceland was relatively peaceful, but still it was a highly hierarchic society where the minority of wealthier decided the fate of the majority of poorer. The funding principle is "you can have justice if you have the resources to pay for it") ,
I'll try to elaborate more later on.