Evolution of the Business Case

It's interesting to think about D&D's evolution from assuming you were selling adventure materials almost exclusively to DMs (at a presumed 1:20 player ratio! OD&D Vol. 1, p. 5), to selling lots of player-boosting aids (2E and 3E), to recommending that DM's be removed from the game entirely (Ryan Dancey in August '07).

It's like the business case for finding some way to sell stuff to the big end of the 1:20 DM/player ratio being a superpredator that consumed the whole idea of the original game.