Potentially, a "list" could be made... repeat offenders with "i just don't like their posts" could be added to a special section of the list (after x amount of complaints), and then, ultimately have their rep ability removed for suspected abuse of the system (after xx amount of complaints). Granted, it's not a foolproof theory, but if someone is causing enough stink to get put on the list, added to the "you've been warned" list, and then still go hog wild with the downvotes, they are essentially acknowledging that what they're doing comes with the risk of having that rep ability removed. May be too much work to effectively govern, I don't know.