That's just silly. The fact that you disagree with an opinion does not mean that other people should not get the chance to be exposed to it. That's how echo-chambers form.
At the same time, the amount of disagreement an opinion gathers is an extremely important channel of information for determining whether you agree with someone's position. Silencing the disagreement with it gives an outsized benefit to harmful and malicious statements.
That's fine when a disagreement (or downvote) is just a signal on the post, but when it's used as a way to silence an opinion (e.g downvotes will hide it) that's even more harmful and malicious. Especially when the guideline is to downvote posts that are low-quality or don't conform to the rules, not posts you just merely disagree with or are against your belief system. Popularity should not be confused with truth.