I'm going with hindrance. Studying literature and studying writing are separate things and I think sometimes what we may learn in lit classes can contaminate us as writers. This is based on my own experience as I've encountered a number of lit instructors who were so rigid in interpretation and in what is considered literature that it turned me off some certain books (screw Steinbeck and Dickens). I wouldn't classify any of the books undergrad instructors had required as essential reading for writers. Ethan Frome? Please. This isn't to say that reading isn't important in becoming a writer. No. You need to read everything you can find, that means even holding your nose to read Steinbeck.
Plus, lit classes teach (at least those who pay attention) that there is a hierarchy in literature, with genre writing somewhere around grocery lists and ransom notes. That whole litfic versus genre fiction fight begins here. If you want to get rid of constant discussion, you need to kill it at the source.
And another thing: I truly believe that a lot of people are turned off from reading by lit classes. If I hadn't already been a bookworm and knew that there was so much great stuff outside of the classroom, I don't know if I would be a writer today. But think of the people whose first experience with reading is from these classes. No wonder reading and book buying are on the decline.