Anarchists don't want a king. Neo-feudalists want to be the king.

Anarchism is not just “no government”, but rather “no rulers”.

Leftist anarchists are acutely aware that power and capital accumulation go hand-in-hand.

Extreme libertarians are perfectly fine with the unfettered accumulation of capital and seemingly ignore that that results in unchecked power. Or they have faith that a “truly” free economy would somehow check itself before becoming effectively neo-feudalistic or dictatorial. As if the lion would fear the zebra.

Leftist-anarchists want to keep power to an absolute minimum. Usually relying on a combination of culture and group action to wield just enough power to prevent the growth of unchecked power in the hands of a few.

In my mind, culture is the key element. The capital-worshipping, me-versus-all culture we live in would fit quite well into extreme-libertarianism and then it would devolve into defacto rule by a few. (As seems to be happening anyways. Because, again, capital accumulates, protects itself and takes power where it can when no one is willing to or allowed to work together to stop it.)

Leftist-anarchism requires a more mature, selfless, introspective, cooperative culture. Anathema to the “United” States of America.