"The appropriate reaction to comments one does not like is downvoting them."
If you are an whale maybe yes, but if you are an small user and have to fear, that the whale whome you downvote will react and downvote you and maybe "destroy" your account (means f.e. bring your reputation under 0) you better don't downvote.
This is the question here, that accounts who have enough Steempower can do what they want and only the small user are affected.