It does seem like the sort of thing that ought to be included in a manual, doesn't it? My best guess is that they probably discovered it after the manual and such were set (I got the impression that it's ... difficult to get such stuff changed once they've been accepted at a certain level), and decided that making a point of telling us at the Blogger's Day (and having us spread the word) was the next best thing they could do.
Most of that's guess-work.