You are thinking only of one type of anarchism, ie the socialist type. There is also individualist anarchism. Which would be closer to libertarianism (although libertarians would support some state activity so it’s somewhat different).

Hence why the "individualist" strain of thought essentially died out as all other anarchist philosophers moved to anarchist communism.

It was revived only recently with "anarchist capitalism" which is of course a contradiction.

If we were having this conversation in the 1820s before such abominations were dreamed this distinction would be worth making. Nowadays, when people want to talk about "social anarchism," they say, "anarchism," and when they want to say "individualist anarchism," which as been identified for the right wing ideology it is, they say "American libertarianism."