Early on mods encouraged users to upvote everything to counter brigading. Then they noticed that it got them on /r/all. So now they just randomly post notices of brigading.
Just wanted to also throw out there that the mods' technique was to sticky a post for everyone to see and upvote. The Admins told them that abusing stickies in such a fashion (frequently, and without good reason) was considered a form of (up)voter manipulation.
