Because in a stroke of genius our Queen, Great Queen, Queen of Thet, Great Site Admin, Beloved of etc ? ? ? ? ?

Anyway, because she implemented reference with the mechanics of a universe and so every time a contribution is made all the contributors get an update. Hence it does not send a PM to everyone, but just those who have the power of editing reference. Given though that a) a lot of people do and b) really nobody gives enough of a crap about reference to want to be alerted every single time a sack of rice falls over (especially since given the amount of people who can edit it this happens all the time) and furtherm- RHETORICA FIX THIS ALREADYYYYYY