I think the genre divide is not just coincidence, but also not the fundamental reason for conflict and change. "Story first" seems to me more basic, a view that one can have regardless of what (if any) genre fiction one has read.
Just as we can identify precursors of D&D, we can find precursors of Hickman's work. There's a period of relatively unrecognized experiments, and then -- a paradigm-shifting product. Dragonlance was that for "story first" in D&D, and thus (because D&D was most visible) for the RPG hobby.
Now (as demonstrated in at least one earlier post in this thread), some people even consider the approach definitive of RPGs. The original "role-playing" concept has in some quarters been supplanted with an essentially theatrical one.
Once a former innovation has become the long-standing norm, it can be easy to forget that there was a time before it.
Coming from ordinary wargames, one found in D&D something distinctively different. Seeing things from the perspective of one's playing piece was not just a small part of the game -- it was the game. Here you are; what will you do? No army to command, no set victory condition, no limit to the field of operations ... no end, really, to the game at which point one could be said definitively to have won or lost. One could indefinitely keep rolling up new characters via which to explore the worlds of adventure.
That was not something one would expect, much less take for granted; it was a revelation. (I refer here both to personal experience and to many, many accounts of others.)
The "story first" game -- as distinct from the "emergent story" game of D&D -- was also revolutionary. It was not what one would expect, because there was no previous experience that would lead one to expect it, any more than one would expect a "plot line" in Risk.
Indeed, that there was no predetermined outcome was definitive of a game. "White to mate in three moves" was for puzzles, and looking up the solution was not what those were about; it was the resort when one gave up on "playing with" a problem.
I see the methodology of those "plotted" D&D scenarios, which seemed to become very common in the 2E era (in modules, if not in Dungeon magazine), as flawed. There's nothing, of course, to keep other people from finding it quite satisfactory.
To my mind, a design that integrates the "narrative control" concept as part of the game is better than one that subverts the game. When a "good game" requires breaking the rules, I think it's time to change the rules.
In any case, "story first" and "role-playing with emergent story" are rather at odds with each other. I think that is the real underlying reason for conflict and change in D&D.
