Except even the world revolution can't solve the issue of degradation into a plain-old authoritarianism. Speaking in analogies, both communism and anarchism, as geopolitical regimes, create a power vacuum. A sterile room, ridden of all the bacteria, but neither of them has an answer on how to keep the room sterile after without having to overthrow yet another government.

[...] It's also became heavily about surviving and overcoming an international system of capitalist power [...]

As i said in my initial comment, both ideologies can work on smaller (than a geopolitical one) scales. Anarchism is already basically intrinsic to any friend/family group in some capacity. Help efforts, no matter whether they were started by ideological anarchists, exist, and nobody bats an eye about that. That's just not what i'm discussing here. I'm discussing the realism of a communist and/or anarchist state.

No it doesn't, but military is authoritarian by design, it will be much less effective without a strict hierarchy.

Case in point — greek polises. Each of them individually weren't quite anarchist per se, but how they interacted with each other, and how they stopped being independent entities in the end is very illustrative of what happens to geopolitical entities without an established hierarchy.