It's striking to me that the discussion so far (correct me if I missed something) ignores what I thought was the more important bit of the article. I quote (emphasis mine):
The central idea remains constant: videogames began with two-player games, experienced through the proxy of a machine. Two or more humans matching their abilities, with victory and failure adjudicated by hard rules, has remained true, from chess to Pong to Battlefield.
There's another way of looking at videogames: how the vast majority are able to entertain when there's no other human being there at all, just you and a machine. The machine just exists to interpret your actions and turn them into a world for you to experience. It exists to entertain you, to take you somewhere else, to give you a place to explore. It is a storyteller. This is a different approach to the idea of 'game', and - interestingly - its core emerged at a similar time to MIT's Space War, as if culture was suddenly ready to reconsider what a 'game' could be.
They claim, in essence, (if I understand correctly) that DnD helped change our very concept of the computer game; of how the computer can be utilized for entertainment. It's not about hitpoints (pong could have hitpoints). It's about the concept of the computer "as storyteller" -- a concept which underlies a vast array of genres in gaming. Now, this is a significant historical assertion. Is it indeed true?