Communists don't think that political dialogue exists as a genuine process between rational actors. They think that people's political beliefs are a product of their environment and class. This is why they don't like free speech and don't like debates. They think that schools are only capable of indoctrination. Therefore they seek to turn this indoctrination in favor of the workers rather than the bourgeoisie.

Edit: if you disagree, please explain why. Marx believed that history moved according to dialectical materialism where almost all individuals are little more than atoms in a moving body.