It wouldn't work; as far as I know the total downvotes you are allowed to give is function of your own karma; sockpuppets without karma couldn't downvote, and maintaining three sockpuppets that post enough to get karma (by upvoting each other?) sounds like a pretty non-trivial inconvenience.
So, there is a non-negligible chance of newbie become a future troll reading LW?
Has anyone yet mentioned or reported that for the last couple days, the "karma for last 30 days" is showing zero for everyone? And that we no longer can see the top contributors for the last 30 days either?
Do we have an explanation or estimation for a bugfix on this?