If you can understand a system of government without ever reading its propaganda, or a religion without reading its key texts, what is to stop you from running a business without ever reading the accounts? These things have very practical applications for their adherents; much the same way as we use science to understand the world, the communist "worldview"was itself considered a science, and one in conflict with "bourgeois" science.
What has taken me alot of time to accept was that the Communists do not share the same sense of "reality" as Liberals. the amount of philosophy involved is so much that it is comparable to a religious war; both sides cliam to believe in the "one true faith" and it is only by reading each others texts that you start to understand them. Whilst Communism isn't a "religion" it is probably better to think of it as one- as whilst liberalism, conservatives and socialist are political ideologies, they share roughly the same set of philosophical assumptions about human rights, government by consent and morality even if they have a different interpretation of it. Communism, does not share it, which is why it is labelled (and inaccurately) "totalitaria". it is very alien, and for the most part people think it's a dellusion, a religion, pseudo-science, or just plain crazy. Doing so saves people the trouble of thinking about who they are and how they reached their opinions whilst others came to very different conclusions. The truth is more complex as Marxism was the product of enlightenment thinking but departs from the mainstream understanding of the world in alot of heretical ways. like some sort of parrelell universe. (e.g. History is considered a Science). This means it feels something like a maze and it is quite easy to get lost, or to be lost whilst convinced you know where you are. (And for what it is worth, I think most members of the "far left" come under the second catagory).
After ten years, I can say I still don't understand it or fully accept it, but I have learned a whole lot more about how the society I was brought up in established certian bias as self-evident, whilst leaving a great deal "invisible" and hidden in the background. The appeal of Communist theory is it makes alot of things intelligable and that can be quite a "rush" as you suddenly feel you have enough information to change everything; the sense of empowerment is the attraction. Of course, that isn't the same as having expertise to discuss science, art, culture, music, history simply because communism is a worldview and a formula applied to everything else, nor does that sense of being empowered mean that power may perhaps become an end in itself. A sticking point for me (apart from the ethics) was the cliams made about the political and ideological nature of science which, whilst very logical, still clashed with my more "bourgeois" tendencies of thinking there is a universal science "above class ideology". it's eerily similar to debates over creationism and evolution, but they could still be right- it's just a big risk to take because of how controversial it would be without having the background scientific knowledge to argue it convincingly.