I have read Stephenson's philosophy on Vapor Barriers before, and had discussions with people in the Backpacking business on the subject. The latest version is longer but doesn't add much to the argument. The premise is unsubstantiated. He says, "if humidity next to your skin reaches 100% (meaning it can’t hold any more water vapor), evaporation stops, chilling stops, and “insensible sweat” stops."
That is probably not true. Anesthesiologists have studied this for years and actually can tell you exactly how much you sweat under all temp/humidity conditions. That evidence does not support Stephenson's claims. On the other hand, I find it most interesting that many arctic adventures say they could not get by without a Vapor Barrier; so there must be something to it. Interesting. I always immediately get condensation with a VB, even when sleeping in the relatively cold outdoors.