An interesting article. There is one thing that I wish they would have delved into a little more and that is their very brief discussion about Dungeons & Dragons (D&D). D&D is a simulation based RPG and its origins comes from tabletop miniature historical wargaming such as Napoleonics, Ancients, and World War 2 to name a few to better juxtapose early RPGs and board games from contemporary ones, and better establish the difference between simulation and narrative games.
Oh, I almost forgot, I wish that they would have mentioned Empire of the Petal Throne as it introduced concepts that are now common place in many RPGs.
Jonathan