So what, then, do we make of the short historical period when D&D wasn't the undisputed king of the RPG market---the mid/late 90s White Wolf incursion?
Was it actually the case? Were more people actually entering the hobby through Vampire: The Masquerade than through 1e/2e? I'll admit, I was completely out of the RPG scene around this time, other than playing Baldur's Gate for PC, so I'm asking for outside perspective.
From what I've read of the system and of commentary around it, in some ways Vampire seems to play against D&D's core strengths---
Genre: D&D = generic fantasy (though constrained within its own tropes) vs. Vampire = highly specific, modern gothic/horror
Adaptability: D&D highly driftable (though effectiveness varies) vs. Vampire = I can't think of a system where a game company tried to drift Storyteller. In fact, didn't White Wolf wave the white flag at one point and adapt World of Darkness to OGL?
Branding: D&D was still D&D vs. Vampire had the entire Anne Rice cultural zeitgeist backing it up.
Usability: D&D largely fulfills its internal promise for at least levels 1-9 vs. Vampire---if The Forge proponents are to be believed, Vampire was at odds from the very beginning with itself in terms of what the system promised vs. what it delivered. (I can't comment on this, because I've never once played a Storyteller-based game and probably never will.)
So what was going on? Was it really just an odd confluence of cultural incidences that came together at just the right moment and White Wolf capitalized on it?