There will have been thousands of ninja patches a year from now. They simply don't want people to know certain things were ever in the game.
Several bosses that would grant 1 skill point per kill, a big exploit - it was fixed very fast and never made it into any patch notes. They need to keep that kind of thing out to make the majority of ignorant players think the game is managed better.
It would also save time for ZOS allowing them to work on more important things. Imagine thousands of tickets being sent in by people asking if the exploiters were banned or had those skill points removed.
On a lesser scale, ZOS don't want people who didn't already know vampires are game breakingly OP. They still are, I suspect it's just a quick patch while they work on the actual nerfs.
Also you don't need to know about patches to vampires, it would take a hell of a nerf before you could stop just facerolling your keyboard for kills regardless of your skill. Once vampires are nerfed, stick to zergs if you rely heavily on a broken mechanic.