delericho
Legend
In the US, having turkey on Thanksgiving is traditional. Loads of households don't have turkey, they have something else, and there are lots of other things to choose from - goose, duck, roast pork, ham, roast beef - the number of other things that are eaten on T-day is great. Turkey is one option, vastly outnumbered by other options. But turkey is still traditional, right?
I wouldn't know, not being in the US.

If you count "number of games that use this form" then, yes, D&D is in the minority. But, most of those games are small potatoes in the RPG market.
Ah, but there's the key: most. But even if you look at the ones that are big(-ish) players - Pathfinder, Star Wars, Shadowrun (plus White Wolf, WFRP, and Call of Cthulhu, back when they were bigger than they now are) - those don't use the three-book model.
It's not just that D&D is the minority; it's a minority of one. If I were going to buy a new RPG, or I were going to publish a new RPG, I would expect to do so in a single volume.
However...
I am not convinced that having that argument is constructive, mind you. I just thought it valuable to note that it may not be all that simple. There's multiple ways to look at it.
Agreed on all counts.