Well, it kind of does. Not in the internet points kind of sense, but if it ends up being used frivolously rather than with the purposes set in the etiquette, it may end up changing the character of the discussion. So while the single downvote might not carry weight in this particular instance, maintaining the notion that they do carry weight and are consequential and as such should be used responsibly does carry merit. One possible way of doing this is requesting further clarification in cases where the downvote hasn't been obviously warranted.
Well, it kind of does. Not in the internet points kind of sense, but if it ends up being used frivolously rather than with the purposes set in the etiquette, it may end up changing the character of the discussion. So while the single downvote might not carry weight in this particular instance, maintaining the notion that they do carry weight and are consequential and as such should be used responsibly does carry merit. One possible way of doing this is requesting further clarification in cases where the downvote hasn't been obviously warranted.