If a person works in a factory or a retail store every day for their entire life, none of the work that they do will lead to the discovery of the historical development of the capitalist mode of production. In their work they do not conduct the experiments which would lead to this knowledge. An understanding of historical materialism and political economy can only come from a scientific analysis of philosophy, history, and the conditions of the working class.

If you need a quick explainer on the communist theory of social revolution, I think this is a pretty solid one. Part II can be read here and gets more into specific US contexts.