I think the recent alleged plagiarism incident is a good example of one of the very rare instances where massive down-voting is appropriate since it was in-effect community self-regulation. But in this case I have yet to hear of any good reason for the systematic downvoting of merlyn's posts.

As for experience points themselves, they are what keep this site running. Upvoting, downvoting, voting for consideration, approving nodes, frontpaging nodes, etc. are all tied to experience points. And for many they act as encourgement for greater participation. Thus the experience point system is the underyling operational framework for Perl Monks and any abuse of it should be monitored closely.