The humanities and the social sciences are unusually accepting of obscurantism - that is to say, texts that are deliberately obscure and difficult to read. Outsiders typically label this stuff 'postmodern' or 'postmodernist', but that term isn't accepted by most obscurantists, as it is really only one obscurantist movement among many, including post-structuralism and, I would say, structuralism as well. But since the texts are deliberately difficult to read and contain few genuine chains of argument, they're all much of a muchness, differing primarily in style and purported subject instead of approach. So they can be treated similarly, I think.
Obscure texts are the bane of students' lives in the humanities and social sciences. Students complain (usually in the pub) about having to read the works of, among others, Judith Butler, Julia Kristeva, and Gilles Deleuze, because the writing is dense and the meaning is difficult to see through the wordfog. Academics tend to love this stuff, though, and a number of disciplines and departments are largely taken up with teaching and writing about obscure texts and the ideas supposedly drawn from then, including social anthropology, women's studies, and some history and sociology departments. Classics is perhaps most immune to this stuff, due to the fairly elite, conservative background of a lot of classicists (meaning that they're not exactly prone to obscurantist non-arguments in favour of Maoism).
The success of obscurantist texts and authors in academia is something of a mystery. It's so obvious an example of the Emperor's New Clothes, a story we're surely all familiar with, that I find it incredible that anyone falls for it. How could academics, people with doctorates who have spent the bulk of their lives studying and bettering themselves intellectually, endorse texts that they don't understand?
One theory, the 'idea effort justification' theory, is that the very difficulty of the texts makes any knowledge gleaned from them inherently valuable. This theory has been written of in Skeptic magazine and can be found online - in fact, it was in this week's eSkeptic, and you should probably read about it there.
The theory is this: the time spent in deciphering a difficult text has to be justified somehow, meaning that an especially impenetrable text will seem especially wise. As long as the sentences are more or less grammatical and contain words that are individually meaningful, it is easy for the earnest knowledge-seeker to believe that they've found great truth in the text, and, given the obscurity of it and the apparent lack of any real meaning, this truth will probably correspond quite well to what the knowledge-seeker already believes. Since we like reading things we already agree with, it is easy for this fundamentally irrational process to override any prior scepticism towards the texts and authors. A similar process probably underlies religious texts and their use.
Since the people introducing students to these texts are often authority figures and gatekeepers, it's not hard to see how they seduce the unaware. And once the students have used those texts to acquire qualifications and academic positions, there is a yet stronger need for effort justification, as all the hours spent studying those obscure texts have to be rationalised.
When a prepared mind starts reading an impenetrable book by Deleuze, the person is undergoing something akin to a religious experience. Where a more reasonable approach to the text would show that there is nothing even approaching sense or meaning in any of the sentences, it is hard to dissuade the true believers, just as it is hard to reason religious people away from their beliefs. This is why Sokal and Bricmont's Intellectual Impostures, a modest and sensible book about obscurantist abuse of scientific ideas and terminology, was well received by neither the obscurantists themselves nor their true-believing followers, even though its arguments were clearly correct, and even though it definitively showed that a lot of the supposed erudition and nous of French leftist obscurantists was an illusion.
The latest fad in the social sciences is 'ontology', a word that means something completely different to its obscurantist use. The abusers of the word 'ontology' have stretched it so far as to mean almost nothing, even though its original meaning is very clear. They use their abused word to cover a variety of obscure positions that are nigh-impossible to make sense of and which have either trivial or absurd interpretations (nothing original or compelling on its own terms is likely to be found in an obscurantist text, of course). This 'ontology' is just a fad and nothing more - just another trend for students to have to learn despite its uselessness.
The academic job market is highly competitive, and obscurantism is a convenient way of getting ahead without needing to be original or knowledgeable. It makes sense to me that a student wanting a life in academia would indulge in this stuff even though it makes no real sense to them and even though they can only explain their 'theory', as they so often call it, in the vaguest and most jargon-ridden terms. But it also makes sense to me to promote facts and knowledge above superficial erudition and literary trickery, and to attempt to find out what is true instead of devising ways to disguise a lack of originality.