But this discussion is about game dev, where apparently you don't need to hire rock stars?

Or I'm missing some important point here?

Why is that true? Games can potentially be hard problems and might need very aggressive optimization; as well as your creative staff might need to be creative enough to attract a lot of people to your art. Even if you use a game engine for everything, employing a rock star engineer in something like Blizzard certainly will not make WoW development any worse.