According to
Communist theory, the
dictatorship of the
proletariat was the final,
utopian stage of the
Revolution. Massive
upheaval would be necessary before this stage could be achieved, but the ends (a "
worker's paradise") would justify the means.
The upheaval would be managed, after the initial overthrowing of the pre-existing regime, by a revolutionary elite. This elite would be in charge of, among other things, eliminating counterrevolutionary influences and indoctrinating the proletarian masses so they would be capable of exercising their rights as part of the dictatorship of the proletariat.
The part where this collapsed, as with most utopian systems, is where it assumed that humans were all inherently good, and could be educated to act consistently for the benefit of the entire society and not themselves. In practice, no state-scale Communist system has ever advanced past the revolutionary elite stage, because the elite themselves decided they liked power too much to hand it over to the proletariat.
Perhaps the economic structure of theoretical communism could work in a perfect world. But the world ain't perfect. Instead, all it did was provide a theoretical justification for the atrocities of the power-mad, in the Soviet Union, China, Romania, Cambodia, and many other places.
Perfect-world thinking is dangerous... see gun control in the USA...