This does not mean that every society must go through this but rather looks at societies as a whole. For example, one could argue that the USSR “skipped” that step, but it’s not something that as a whole could have been avoided.

The logic behind this is the same as for why slavery, feudalism and so on where necessary steps in the process of dialectical struggles that led to the one we are trying to achieve.

Marx understood the dialectical approach of Hegel, but he wanted to ground it on reality, on the material reality of existence. The way this would work is to understand that everything is matter in movement that undergoes changes. The same could be said of individuals, and of social bodies or societies.

It all starts with primitive communism, where there wasn’t any private property and everything was “distributed” because humans of any group hadn’t seized any kind of means of production. So in one way or another, a couple of small groups of people, along with technological advancements (like agriculture, farming, etc), manage to accumulate small quantities of capital, which puts them on a higher social hierarchy and allows, along with the use of force, to enslave people. And so on, and so forth, every social system hitherto existing was an evolution on the preceding one that allowed for an accelerated and greater accumulation of capital than the previous one.

These systems existed because of the necessity in a world with limited resources to allocate due to either poor extraction techniques or limited knowledge on how to do that or produce energy. Capitalism is no different than feudalism, the only difference is that it’s characterized by its accelerated velocity at which accumulates capital in the hands of the bourgeoisie, which in turns accelerates its own demise by creating greater class contradictions that collide and will bring the inevitable end of its dictatorship. Capitalism has solved the scarcity problem, we no longer need a class based system to overcome nature’s entropy. Basically what’s going on is that it allows for a faster accumulation of wealth and capital through centralization, which then goes on to pass to other hands, i.e.: the next synthesis in the dialectical struggle of class antagonism ([…] - feudal lords, thesis; bourgeoisie, antithesis; capitalism, synthesis - bourgeoisie, thesis; proletariat, antithesis; communism, synthesis).

The way I assume you are thinking about this, is one where you intertwine an anthropocentric moral with the fact that capitalism allows for exploitation, whereas a correct comparison would be to look at it the way nature works in some aspects. A wolf is not ethically wrong to kill it’s prey, or a duck is not ethically wrong when it’s raping its female counterpart to reproduce.