Memes

There are 2 big errors here. The first is the idea that Actually Existing Socialist states, the ones governed by Communist parties historically and presently, have nothing in common with the "ideal" of Communism. The second is the idea that Communism is an ideal. I bring this up because your perception is very common, especially in the West.

People not trained in Marxism-Leninism tend to see Communism as a perfect model to emulate, ie a "utopia," while Marx himself was strictly anti-utopian, instead firmly believing in taking a scientific approach to Socialism. This means that different levels of development and situations will have different structures of society, but all will generally hold the power in the working class through a proletarian government.

In reality, states like the USSR absolutely followed Marxist analysis when deciding what to do and when. This is abundantly clear when reading historical documents and rationale. This can be further obfuscated by western propaganda, like the idea that Socialism concentrated power into the hands of the few, when in all cases it has represented a democratization as compared to previous systems like Tsarism.

The combination of the "Red Scare" vision of all AES states being the default, combined with a thoroughly "liberal" vision of Marx as some Utopian as the default for understanding Marx in the west, leads to a very difficult time with growing Marxist movements.

As a side note, idealism doesn't refer to literal ideals, like goals and such. Idealism instead refers to philosophical idealism as opposed to materialism. The idealists believed that ideas come before matter, ie everyone exists in their own mind palace perception of the world. The materialists like Marx believe the opposite, that matter creates ideas. Social practice like labor creates social consciousness, this is why Marx believed the proletariat as accustomed to cooperative labor form a genuinely revolutionary class towards socialism, while other classes do not to the same extent.

Second side note, all states are authoritarian, all states are the means by which one class asserts its authority. It is good for states to be proletarian.