Authoritarianism is a measure of how monopolized and heirarchical the decision-making process is within an organization. There's nothing meaningless about that, it's a very specific thing. Now if you use the definition from Engels, where your stomach is authoritarian when it's hungry, it's definitely meaningless, but to pretend that is the only or even the main definition is just asinine.
Indonesia or Guatemala
Are you referring to Jacobo Arbenz and Sukarno? Those were pacifists who refused to arm themselves. That has nothing to do with decentralization.
If you don’t understand the material trends of society
You can't! No one can! Society is not a monolith! It's billions of people with different thoughts and feelings and ideals and desires and conditions, you can't condense them all into a theory, you're not smart for thinking you can. Guessing that society will definitely surely follow a very specific process to the letter is again, purely self-masturbatory fatalism. It's Not Even Wrong.
I've met countless libertarian proletarians, I was one of them in fact. Because societal trends are just trends, and society doesn't simply collapse into what the majority of people (not that a majority of proletarians are socialists at all) will it to be, in fact, that happens very little. If your theory were true, states would have never developed in the first place, as they were against the interests of the vast majority of people living in stateless societies.
It's okay to see trends and predict based on them, but to think the trends indicate a very specific thing is GUARANTEED to eventually happen, and to think henceforth that any other investigation of alternatives is pointless, is what I call self masturbatory fatalism