because they think it has some sort of brainwashing effect or something.

Unironically yes, because of how leftist literature differs greatly from the cartoonish picture reactionary concocted of them. Trying to read Capital and got absolutely fucked by the dry-ass economic treatise genuinely dewormed my brain. I cannot get past the part about diamonds yet reading just how thought-out Marx actually is in contrast to the slander of him as the "free stuff" guy.