You just misunderstood what they're talking about. The issue is that vanilla was not a single thing, it was 12 major patches, none of which represents the one "authentic" vanilla WoW. The kinds of questions they need to answer are: Do we put the catchup mechanisms of the last patch into the game at the start, even though it would trivialize a lot of the earlier content? Do we cap UBRS at 15, 10 or maybe 5 players? Do we release all the content at once, or introduce them over time?