I've downvoted everyone in an entire thread before. Not because I'm a member of a shadowy organization (otherwise I'd be blowing my cover posting this) but because all of them were really bad. HN being HN, usually someone will take the time to write a good comment, but especially on emotionally charged topics, the earliest comments will be both short and just a reflection of the posters views
before they read the article (if they read it at all) which makes it likely I'll consider them downvote-worthy.
I think there are probably quite a few users who behave similarly. But there's no need for us to form an organization, because each of us can just use the user-moderation tools as intended, without having to coordinate our actions with each other.