Hmm, how about one user downvotes, provides the appropriate reason, then others can "join or agree" with that user's downvote by upvoting his/her comment. Maybe

Hmm, how about one user downvotes, provides the appropriate reason, then others can "join or agree" with that user's downvote by upvoting his/her comment. Maybe this could somehow count as multiple downvotes with the same reason?