but I’ll say it again: your analysis of socialism fails because it relies on “one-drop” analysis.

All of the “socialist countries” that you defend, do not just have “one-drop” of capitalism. They inevitably reproduce and enfranchise the capitalist social relationship in all aspects of their production, and their populations are dependent on the market to survive. Whether that is done by state planners or private capitalists, the exploitation of the proletariat class continues, in fact following the laws of capitalism, like the continuous immiseration of the proletariat and the inevitable necessity of imperialism under Capitalism.

A socialist economy cannot just will the productive forces to levels where public ownership is the most effective, I agree, but I disagree that that means that an underdeveloped country cannot retain ownership of the large firms and key industries, gradually appropriating capital with respect to its development. It’s like using fire for heating, keeping it in check by controlling the environment and all inputs, fuel, etc, and gradually replacing it with electrified heating as time goes on and you get the tech for it.

Why do your “socialist countries” not appropriate capital then? Why do they inevitably concede to private ownership, or even under the “state run monopolies” continue the capitalist social relation?

I fundamentally cannot agree with treating socialism itself as some unique mode of production

Even if we concede that, Capitalist social relationships and Socialist social relationships will coexist under a Dictatorship of The Proletariat, your “socialist countries” do not even attempt this, bar the revision of defining “state ownership” as a socialist social relationship. Yet, a number of countries you would consider “capitalist” practice(d) state ownership.

Which reveals your ideology for what it truly is, Capitalism with red paint, essentially, social democracy. If socialism is not a mode of production, what is it? An ideology. Agitated for in bourgeoisie parliaments as ethical capitalism with red flag characteristics. What would be the end of a “Socialist State” to you? When they change the flag color? If the “Communist Party” changes its name to the “Capitalist Party”? You have no material conception of what Socialism and Capitalism is, which is why it collapses into idealism to the extent you even refuse to accept that Socialism is an independent mode of production in of itself.

Capitalism is a historical progression

Progressive =/= better. The Capitalist social relation inevitably reproduces itself across the globe because of the social forces. Not because it is an improvement.

Therefore, this expansion of productive powers in capitalism in theory leads to better life quality, less socially necessary labor time to provide for everyone, less mortality given how we can now produce things like insulin in complex labs, etc.

Regardless of the debate that these modern conceptions can be attributed entirely to a change in the mode of production rather then simply the inevitable progression of humanities technological knowledge, Marx actually argued Capitalism inevitably immiserates the proletariat rather than advancing quality of life.

You try to hedge this by saying “in theory”, yet not even in theory. It is a lie of the bourgeoisie the proletarian slavery is an improvement over peasant slavery. In theory, Capitalism is simply the reproduction of the capitalist social relationship and the replacement of the nobility class with the new bourgeoisie class.

Btw, comparison between feudal peasantry and proletariat is flawed - peasants were based in countryside and essentially were the middle class of it

The comparison is not to equalize the proletariat and peasantry in their relationship to the means of production, but in the demographic comparison for who is the majority of the planet. In Feudal times, peasants, including serfs make up the majority of people. And serfs are decidedly not middle class. Peasants were an exploited class under feudalism, duped by the bourgeoisie to support the inevitable capitalist revolution that would “improve their quality of life”, only to find themselves alienated industrial laborers and at the bottom of class society once again.