On another post about downvotes I answered on your comment as follows:
@wulff-media Some accounts with high SP seem to exist only to use their power to heavily downvote those they hate (for whatever reason) - and one (or more, like maybe same guy with several accounts) I am aware of seems to be a stalking troll who does not post himself at all, but just uses his big SP to downvote. Giving haters (that can afford to invest large amounts in Steem) that much power without any kind of checks and balances can also damage this platform.
The incidences of heavy weighted downvotes I am aware of are seemingly politically (and perhaps also racist) motivated actions by one (or more?) ultra-right-wing actors.