I think he meant they're trying to avoid being like Peter Molyneux - that's the effect Molyneux has had. He made people cautious about giving out specific details.
I can see where they're coming from with that - even if they're not overhyping. Every detail they give out sparks some bad reactions from people who don't like this or that feature. The fewer specifics, the less angry people before release. The less angry people before release, the more sales. The more sales on release, the more they can cry "success", and then more sales. Also, the critics won't have had time to formulate a really coherent attack on the game as a whole. They'll have to speculate most of their points, which will therefore probably be wrong.
Conversely, you release lots of details, well it might help you design a better game because you'll get more feedback, but it will hurt the reputation and therefore success of the game. More people will rage at features they don't like. They'll rally against the game, and by the time it is released, they'll be able to create an air of disappointment. Also they'll have had lots of time to make their critique more coherent and it will be targetted at real, rather than mostly imaginary, features.
Alot of people just go with the flow, with what they hear, and convince themselves to think the way they hear. Most of us, probably, do it to some degree, unconsciously.