I've got plenty of qualms about the way Facebook has handled it, but of course there was something wrong with the rules -- they had never tried them out under these circumstances. All three of the things you cite are using/abusing social media in ways that have never been done before.
Principles are great, but if you can't change your principles when the world changes around you, then they're not so much "principles" as "dogma". The world is a complex and difficult place, and I don't expect any simple set of principles to be adequate to all of the things I don't anticipate. I try to anticipate everything I can, but it's no surprise that I'm sometimes surprised.