Authoritarianism is a measure of nothing. Do you not just mean authority? For something to be an ism there has to be something constant about it, but authority is a response to external conditions, and when it comes to the state, can’t take on an independent, alienated character, but must conform to the character of the dominant class. This is precisely what Engels was trying to get across with his comparisons.
Authority is not a response to external conditions, it is a system of domination and subjugation self perpetuated by itself. The constant about it is in this relation of power over groups of people, the power to enforce your will on those regardless of how it affects them, given the hold of an use of violence and coercion to enforce that will, that is perceived as legitimate. Authoritarianism thus measures how much this is enforced and by how little people - as what I said, it measures how monopolized (owned and usurped by a small group of functionaries) and hierarchical (based on a pyramid structure where decisions at a higher level bind the lower levels) the process of decision making is within an organization, be it a party, a state, a minecraft server, whatever.
This is a very specific concept that measures a material thing you can see and experience. There's nothing meaningless about it. I gave you this definition, and you simply refused to use it and reasserted the same thing. I'm starting to think muddying the term is intentional....
Do you think mass movements are a product of people coincidentally independently coming to the same conclusions?
I merely don't think they're predestined to happen in a certain way (coincidentally the way I want them to happen, but I'm sure that's just a coincidence!) nor do I use this thought as an excuse to immediately discard any alternative methods of organization without even considering them.
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