Also, due to UI issues, it's aggravatingly easy for iPhone users to accidentally vote on a comment. I've become incredibly paranoid when reading HN on my phone these days just because I've accidentally driven so many commenters ballistic with random downvotes. Getting mad over one or two votes just doesn't make sense, even less than getting mad over HN votes in general makes sense.

(Incidentally, and ironically given the subject matter, this problem doesn't seem to exist on Android. I wonder if Apple has a patent on forum rage.)