This take is simplified to the point where its ridiculous.
>where you can "age up" after a certain amount of surplus?
No. You have it the wrong way around.
You don't need to have XYZ productive forces to enforce an ABC type of system. You don't need to go through full on capitalism in order to achieve communism, like Marx vaguely implied, and vulgar marxists believe to this day. Lenin and Mao proved as much.
Rather, the material conditions of a society have contradictions in them. As technology and the situation evolves, for example, as the bourgeois elements of feudalism grew in power due to trade and production in cities, as profits dwindle and monopolies form, the old order of things, the old mode of production, the way politics is organized, cannot remain as it is. Fractures grow larger and larger, tensions grow higher, forcing the people in that society to change things around radically, creating a new mode of production. Feudalist law and society cannot handle capitalist growth in its model, the capitalist model that grows out of it destroys the feudal model by molding the bourgeoisie into a group in opposition to the then rulers. Just like how capitalism molds the working class into a class in opposition to the bourgeoisie. In this overthrow, a new society is formed. From slave societies to feudal societies, from feudalism to capitalism, from capitalism to communism (this is the traditional broad european path).
A true scientific marxist would see these transitions arent clear cut. The principle of the political system not fitting the way things are produced, creating opposing classes that clash when the contradiction grows too strong, is the core of the matter. Thats why in china and russia, the peasants joined in the communist revolution, even when they had had no capitalism yet in most of their country. The contradiction and breakdown of the old order allows for a new order to be created, but said order can be anything. Under most events in history, the only way forward is a negation, the destruction of the main apparent problems with the old societies. Feudal early bourgeoisie and peasants could not foresee the issues of highly advanced capitalism, it could only the see absurd ideas of the divine right to rule, caste systems, and arbitrary ownership by kings, and thus in its place put the liberal ideas of castlessness, equality before the law, the right to own your own property without the kings or anyone else taking it when they fancy. They could in their situation only see the new society in the flaws, in the negative, of the feudal system, just like we can only see socialism in terms of the negation of the flaws of capitalism; common ownership, no more markets and money, production for use. We cannot truly see beyond it.
But in china and russia, even if they were feudal, europe already had capitalism. The proletariat already had developed communist ideas. And capitalism was making marginal inroads into their countries in the form of small pockets of local bourgeoisie and (in the case of china) imperialism. The revolutionaries there too saw the cracks in the feudal system, but they had a choice. They need not invent a new society out of the negation of the flaws of the old, that had already been done. And that system had its flaws too. So Lenin and Mao (or rather, their parties) chose to not implement capitalist liberalism, because they could choose to go straight towards a communistic endgoal. The overthrow of the old puts you in a position to implement a new system. It is no law of nature that capitalist liberalism has to follow feudalism. You could implement any number of systems, some fit the situations better than others. But where the french revolution could, from their position in history and reality, only think of the future in terms of negating the flaws of their feudal system, people like Mao and Lenin could look to other countries that had done what they had before, and choose to immediately jump to the fix to their problems.
Keeping this in mind, it is up to us to look at China, the USSR and other socialist states, and ask ourselves: When we overthrow the current system, do we need to go through the systems the USSR and china chose to implement, or can we jump to a system that negates the flaws in their systems?
TL;DR Material conditions, and their contradictions, eventually force a breakdown of the political organisation of a society when it no longer fits its mode of production, but the new political and productive system is not determined deterministically by that old society, but by the revolutionaries. The ideas for a new society need to fit reality, but do not need follow through all the steps others took, as Lenin and Mao demonstrated. Consciousness of the proletariat can be adopted by peasants as their revolutionary ideal, rather than working through 4 ages in sequence.