See, I don't even think it's "dark ages" per se.
I think the key difference is that D&D went from something kinda-sorta-ish like realpolitik and logistics, to something kinda-sorta-ish like romanticism and adventure.
Folks who like realpolitik see romanticism as gaudy, garish, childish, a colorful but unserious profusion of silly nothings that never cohere--even when that description is blatantly biased, inaccurate, and unfair. Folks who like romanticism see realpolitik as dingy, drab, pretentious, a bleak and depressing profusion of self-congratulatory nothings that never cohere--even when that description is blatantly biased, inaccurate, and unfair. Folks who see HIGH ADVENTURE! as the core of the experience find logistics plodding, time-wasting, and just generally pointless busy-work, "filling out your taxes" and the like. Folks who see campaign logistics as the core of the experience find "high adventure" nonsensical, slapdash, time-wasting, and just generally pointless play-acting, "shouting your combos" and the like.
D&D has been offering something to both groups for a while now, but trying to pretend that the two have completely copacetic goals and interests. I obviously think that position is mistaken.