It’s my opinion that the GNS as offered on the Forge was based on a misunderstanding of the RGFA Threefold which preceded it. One part of what wasn’t understood is that the Threefold applied mainly to decisions made by the GM in play and rules were touched on only in that they could support one type of decision more readily than others. (I was involved in those RGFA discussions.)
I can also say, as an outsider to the Forge, that the Forge culture–at least as it interacted with those of us not part of it–was toxic. The Brain Damage essay just sealed the deal after all the time the Forge folk spent prior telling us we were all wrong about how we have our fun and all our game systems sucked. Forge fans should keep that in mind if they think somebody shows a bit of bias against the Forge community.