I think you underestimate Marx's work and power of Marx's method. He was fully aware of colonies and the role capital played in repression -- in Ireland and India among other places. He understood that the liberation of the slaves and the liberation of the working people are part of a single struggle. And he understood the intimate link between theory and practice.
Marx achieved a synthesis of German philosophy, British political economy, and French socialism, which constituted the most advanced currents of Western knowledge at the time. And he forged the synthesis from the vantage point of the worker, thus providing an analysis from below of human history and modern capitalism. In doing so, he pushed scientific knowledge of social dynamics to a more advanced stage. This more advanced knowledge recognized that modern capitalism represented only one stage in human history, and as it evolved, it would generate the technological and social conditions that would make possible as transition to a society that would affirm and protect the human dignity of all. The transition to a new epoch was to be led by the industrial working class of the advanced nations, inasmuch as they possessed the interest and the capacity to do so.
The scientific breakthrough of Marx constituted a threat to the capitalist class, who had an interest in preserving a system that gives priority to the principle of the maximization of profits to the capitalist. High members of the capitalist class therefore supported an organization of knowledge in higher education that was favorable to their interests and that marginalized the work of Marx. Whereas Marx’s breakthrough implied an integrated philosophical-historical-social social science connected to the social movements from below, the universities established academic disciplines that fragmented knowledge and that were disconnected from the social movements.
With the blocking of the development of knowledge of social dynamics in the universities, the further development of scientific knowledge of social dynamics was left to the charismatic leaders of revolutionary movements, who were leaders in practice but who also made important contributions to theory. When Lenin observed in Russia the revolutionary action of the peasantry, he reformulated Marx with the concept of a revolution forged by workers and peasants, led by a vanguard of workers. When Lenin observed that the European proletarian revolutions of the period 1919 to 1922 were not going to triumph, he projected that the vanguard of the global revolution would pass to the oppressed nations of the world. In China, Mao formulated a concept of a revolutionary peasantry in opposition to the Chinese landholding class, a relatively weak Chinese bourgeoisie, and foreign capitalist penetration of China. In Indochina, Ho Chi Minh synthesized the Vietnamese tradition of Confucian nationalism with Marxism Leninism, leading a revolution of peasants for both national and social liberation. Similarly, Fidel in Cuba forged a synthesis of Marxism-Leninism with the revolutionary nationalism of José Martí, conceiving a revolution by the people against the national bourgeoisie and international capital, seeking national sovereignty as well as social transformation. In Venezuela, Hugo Chávez, responding to the neoliberal attack on Latin America, synthesized Mao and Fidel to proclaim a new form of socialism adapted to the conditions of the twenty-first century.
However, Western Marxists were paying insufficient attention to the evolution of Marx’s theory in the context of the revolutionary practice of the Third World. This oversight was a consequence of the evolving economic and social conditions of the capitalist world-economy. Western colonial and neocolonial domination enabled significant concessions to the middle class and working class movements in the West, facilitating the predominance of reformist tendencies in the working class movements, undermining the revolutionary potentiality that expressed itself in Western Europe from the 1830s to 1922. Thus, Western Marxists became disconnected from revolutionary practice, which constrained the development of their understanding. To be sure, they have been able to understand partially the structures of neocolonial domination, thus they tend to have an anti-imperialist perspective. However, they have limited understanding of the processes of revolutionary change from below that have emerged in China and the Third World, and thus they have an undeveloped concept of the meaning of socialism in practice.
So our limited understanding today is not a consequence of the work of Marx, who established the foundation of modern scientific knowledge of social dynamics. Our limitations are a result of the universities, which have marginalized Marx, and the supposed followers of Marx, who have not been connected to the most advanced revolutionary movements that emerged after Marx.
The Left of the United States today must arrive to understand the evolution of historical social scientific knowledge in the praxis of Third World revolutions in order to have the capacity to formulate a foundational response to the Trump project, as we will discuss in the next post.
See various posts on the evolution of Marxism-Leninism:
“The social and historical context of Marx” 1/15/14;
“Reflections on the Russian Revolution” 1/29/2014;
“Ho reformulates Lenin” 5/7/2014;
“Ho synthesizes socialism and nationalism” 5/8/2014;
“Ho’s practical theoretical synthesis” 5/9/2014;
“A change of epoch?” 3/18/2014;
“Is Marx today fulfilled?” 3/20/2014;
“The alternative world-system from below” 4/15/2014;
“Mella fuses Martí and Marxism-Leninism” 7/9/2014;
“Fidel adapts Marxism-Leninism to Cuba” 9/9/2014;
“What is revolutionary socialism?” 5/4/2016; and
“The legacy of Lenin” 12/22/2016.
For reflections on Mao, see various posts in the category China.
For a description of the characteristics of socialism that takes into account its evolution in practice in Russia, China, and the Third World, see Chapter 9, “Socialism for the Twenty-First Century,” in The Evolution and Significance of the Cuban Revolution: The Light in the Darkness.