Memes

To understand this you need to understand the theory. Marx outlined that socialism and communism each had to be transitioned to after reaching a given level of social/economic development. In particular there is the notion of "withering away of the state" which would happen after a global revolution, which is the aim of this classless/moniless society they outlined.

The communist manifesto is a short read!

In fact the USSR implemented explicit market policies, a sort of contained capitalism, which was designed to facilitate reaching the necessary preconditions for socialism and communism. Essentially all of the "communist" states we've seen so far have been some play on the notion of just "socialism in one country" in the Marxist-Leninist version of communist parties, who have/had the goal of eventually reaching communism.

What's probably most interesting is that the idea behind the USSR wasn't initially to have the state direct everything from the top, but in fact to facilitate worker councils (soviets) to direct their workplaces.

But you have to remember this all happened in the context of a state which had recently undergone a revolution, was rife with counterrevolutonary action (see revolutionary France and civil war Britain to see how this played out during the birth of liberalism) and was then plunged into WW2 where most states involved were acting fairly dictatorially for the duration of it. Followed shortly by the US making it an explicit goal to prevent world communism through e.g. CIA intervention because they feared "domino theory"