It has been argued in the past that a razor can be too sharp. Ray from ClassicShaving often warns against using 0.25 micron diamond paste, as it can create an edge so sharp it catches on every imperfection in your face. A blade this sharp may cause irritation to those with sensitive skin as well. I don't think AFDavis is talking about a dull razor, but rather one that is not super-ultra-mega-mondo-sharp.