Downvoting makes comments less visible. So downvoting is the equivalent of taping someone’s mouth shut because you don’t agree with them. Is that really what you are trying to do?

This is ridiculous, especially the comparison with physical violence. Upvoting a comment also makes all the other comments less visible, by promoting the comment you’ve picked, taking up the place where some other comment could’ve been. Nobody’s mouth is taped shut by either upvoting or downvoting, all the comments are still visible, it’s just that their order will be determined by the upvotes and downvotes - and removing the latter from the equation won’t negate the “discrimination” (comment sorting) created by the former.