no. you might agree with someone saying, "this" but its lazy. "just google it" isnt helpful though you might agree with the sentiment. and someone might be making an argument you agree with, but being toxic and vitriolic. you should downvote those even if you may agree with them. it was called upvote and downvote because the feature would cause the comment to move up or down the chain to the top of the post or to be buried. disagreement downvotes are a fundamental misunderstanding and/or abuse of the system, thank you for coming to my ted talk.