Some of the reasons to be the biggest, favourite and strongest ones (open ones as well), being part of Activision (hatest, trolled, etc.) - Activision Blizzard. So any potential leak is giving a leap step in many news, gamer and community websites, talking to them, to the game, to the franchise, to the products and so on, giving in the end to them - traffic, hype, $/€.
Most companies are "closed" companies.