Apr 17th 2009 11:34AM Wasn't Activision one of the founding member of the PCGA? That's kinda what it looks like based on the original announcements. (In which case, I doubt Blizzard really cared about leaving it.)
Possibly Activision first saw it as a good way to get close to big companies, but now that they have Blizzard with them they consider themselves big enough to stand on their own.
(Also, I don't see this as being a loss.)