Eugine may be the only person to have (recently) been using this as a tool of policy, aside from a couple people downvoting him in retribution. If you look at the patterns of people targeted for retributive downvoting (here, here, and here, plus this thread and its relatives), most of the situations seem to fit his MO and apparent set of grievances. Perhaps most tellingly, I don't know of anyone besides Eugine himself who's been mass-downvoted by two users (which is easy to tell from karma on obscure or unremarkable posts).

(I'm not sure about Will_Newsome, but that was three years ago.)