You don't need to downvote something to the point that it is hidden (below zero). Just make a smaller downvote. If it is earning a reward of $ 50 and you think it is not worth more than a dollar you can easily knock the reward down a few dollars or a few cents or whatever without even coming close to hiding it.

IMO the vast majority of downvotes should not to the point of hiding anything or downvoting content with little or no rewards (which is more likely to hide it) but rather reducing the excessive rewards of milkers from pulling too much out of the reward pool and thereby preventing others from earning anything.