Whenever I hear about how communism is great on paper, but was never implemented since it was held by corrupt tyrants, I say "wrong". If one group managed to actually establish a litteral adaptation of Marx's communism, it was the Khmer Rouges in Cambodia.
They applied Marx's teachings by the letter. They may be the only ones who have managed to actually achieve "full communism", so to speak.
And with no surprise, genocide kicked in real fast. About 20 000 mass graves, execution of teachers, mass deportations, executions, weaponized starvation, you name it, they did it. Yet, I challenge any historian to contradict the fact that this was still the real only true communist state.
You want to see the "paper, real communism" in action, look at Cambodia.
Except that Pot's Agrarian Socialism takes away from the centrality of the industrial worker in Marxism to the agricultural peasant. The two are different in Marx's work. Lenin tried to skip a step, Mao more steps, Pot tried to jump over it all. There is a reason Marxism-Leninism and Maoism exist as different labels. Lenin himself was a minor noble, Mao was the stock of agricultural peasants, these lifestyles influenced them to revise Marxism. Mao called for constant purges and revolutions to cleanse tradition - tradition being an especially vilified thing in later modern China - and capitalist elements still within the system. Pot called for an extreme interpretation of the need for Industrial Armies in Agriculture, mostly by removing the Industrial part. (Number 8 of Marx's 10 precepts in the Manifesto).
For the record, this is what Marx said:
"The essential conditions for the existence and for the sway of the bourgeois class is the formation and augmentation of capital; the condition for capital is wage-labour. Wage-labour rests exclusively on competition between the labourers. The advance of industry, whose involuntary promoter is the bourgeoisie, replaces the isolation of the labourers, due to competition, by the revolutionary combination, due to association. The development of Modern Industry, therefore, cuts from under its feet the very foundation on which the bourgeoisie produces and appropriates products. What the bourgeoisie therefore produces, above all, are its own grave-diggers. Its fall and the victory of the proletariat are equally inevitable." - Communist Manifesto,
Chapter I. Bourgeois and Proletarians.
From the outside the differences are seemingly minor, but thus in practice they form completely different results in a slew of different nations that also almost always led to internal schisms in the Communist-Socialist bloc. Hoxha went his way. Tito went his way. Mao his. Minh his. Kim his. Stalin his. Lenin his. Trotsky his. Etc ad infinitum ad nauseum.
Marx at the least saw Communism as a development of Socialism that would arise from an industrialized Proletariat - not agrarian peasantry, belonging to a more Feudal and not Capitalist world. Proles work for wage labor. Peasants work for survival in a form of serfdom, a step above slavery. Proles exist in a much more complex world that offers them unique benefits in organization and lifestyle that arguably gives them untold power that they can grab. Peasants do not, they are arguably inept, and probably have been blamed many times over for their attempts at revolution from within Socialist and Communist circles.
Another problem overall is that Marx
never finished his tracts. The Manifesto was a TL;DR version of what he wanted, Das Kapital, his prime defense and core, was never finished. How can then a system emerge from an uncompleted prophet? Thus the seemingly infinite array of schools that present their own prophets and answers to the question of what they represent. Maoism. Stalinism. Leninism. Trotskyism. Anti-revisionists who try to work with what Marx and Engels set, which again is incomplete. Castroism. Democratic Socialism. Agrarian Socialism. Vanguardism. Anti-Vanguardism. A slew of other -isms. Bernstein who split off and supported Social Democracy, and a slew of others who think that Marx and Engels wrote a good answer for their time but have become antiquated by x, y, z.
A supporter can still point to Twin Oaks or Kerala or Marinaleda. An opponent can claim Cambodia or China or the Union. Academics can pick apart the works of a 100 people and the philosophical reasoning behind every school.