It is not always about the content, but buying votes on something that is 'meh' just seems selfish as it is not going to drive engagement. It just subtracts from the reward pool. Only the vote sellers really benefit. Downvoting it restores some rewards and may persuade that person that their activity is not what the community wants to see. There are some really blatant examples that I think very few people would dispute. I consider downvoting as valid as upvoting as a way to distribute rewards.