Oh no, how will Holla Forums ever recover?

Because statism and shit.

There's no monoploy of violence or concrete structure to anarchist societies. Organization is fluid and voluntary.

The lack of a monopoly of violence implies the presence of violence by third parties.

Considering that everything is decentralized and autonomous that shouldn't be surprising

CANCER
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Okay…

Because the anarchist definition of the state is (in a nutshell) a government that is hierarchically structured and the majority of people are estranged from the decision making process.

So much autism in one forum

It's not a real forum, they scrape their content from Holla Forums. That thread is probably from Holla Forums. Here's the Holla Forums sticky: hollaforums.com/thread/518058/activism/faq-read-this-if-you-re-from-pol-or-reddit.html

Turns out their activism subforum is Holla Forums:
hollaforums.com/section/activism
I guess politics is Holla Forums, anime is /a/, etc..

Which implies a state-stateless dichotomy in which the point a polity becomes a state cannot be objectively defined.

How so? By their definition, if society is organized horizontally then it isn't a state. I have issues with the definition, but I think it's clear under their framework when something is/is not a state.

I don't already see how this wouldn't already be the case. Either something is a state or it isn't. I'm not sure under what definition there's a middle ground between completely stateless and not-completely stateless.

And that makes it impossible for people to take advantage of others?

It makes it impossible to institutionalize it. There still may be wondering psychos

Complete decentralization of violence devolves into "every man defends himself, or allies defend him when it's convenient", which is the state mankind was in in the first place

And?

This is a pretty bold assertion. Have you consulted the relevant literature, perhaps from an anarchist anthropologist to back it up. Certainly Kropotkin didnt agree.