I first read Edwards's essay on simulationism after I'd been playing and GMing Rolemaster as my main game for well over a decade. That essay has the best account of Rolemaster of anything I've ever read. It explained everything that was strong, and that was problematic, about RM play. It also explained why there are so many variant initiative systems published in all the supplements.Not in widespread use likely because it's a largely-discredited set of ideas criticized for (among other things) not having any real explanatory power and therefore failing as a theory.
The complementary essay on "story now" RPGing is cited by Vincent Baker in Apocalypse World as a primary inspiration for that game, which has probably been the most influential thing in RPG design for over 20 years.
In my view these are powerful ideas which have influenced not just my RPGing, but have had an enduring impact on RPG design and RPG play.