this would require moderation, which is something we're not exactly big on here, but what if all new users have a 48 hour period where their comments are moderated, and need approval? I mean, i'm not sold on the idea, but it could be a possible way to implement the above solution and still cater to authors of content.
Blows scalability to shit. There's currently zero moderation, but your solution creates a chaperone situation where somebody gets blessed with the task of reading (and approving) every. Single. Newb comment. Which, during the last tidder invasion, would have been a thousand comments a day whining about vote counts. I wouldn't wish that on anyone, and above a certain traffic level it just becomes mk's 24-hour mute through inertia.