I agree. I am a screen reader user, and I have absolutely no trouble using keyboard commands to submit my comments. Perhaps this suggestion would work better for those who don't use screen readers, and should be configurable via a pop-up menu or something. Or, perhaps if/when a dedicated Dreamwidth app is developed this could be one of the options? I currently have Control-Enter set as the command to post a tweet after I compose it using a dedicated Twitter app for the Mac which is accessible with Apple's on-board screen reader.