One thing I can't stand is how people swear by their lists ("Best albums of the 70s" etc.). I've met people whose ideas of what makes up canon material is virtually dictated by Pitchfork's idea of it, and if you try to argue against it (I, for one, will never believe that 'The Moon and Antartica' is classic anything), they become very very upset indeed.
The main problem with Pitchfork is how people rely on it so heavily that their ideas of the music they listen to are already decided by the articles they read before they even hear it. Many indie rockers that I've met seem to hate being one-upped or caught not knowing something someone else does, so a lot of them rely on Pitchfork as a cred bible of sorts. Which is obviously a problem with ALL music journalism, but Pitchfork in particular appears to have a much stronger influence on the readership than most music journalism.