ECS was an AM effort to "simplify" Lindy for audiences that weren't quite down with the kicks, throws, tricks, or basically "high energy" that was (and still is) popular with Lindy.
I have seen text that states that, even back in the day, most dancers sat down when bands played really fast songs.
You've probably also "heard" that that many or most ballrooms banded "jitterbugging".
(I've only seen one actual article in a newspaper that states this - in the "Oregonian".)
If "most" people sat down, and you couldn't do tricks in popular ballrooms, I wonder how much "high energy" stuff could have been around.
I've often wondered this, and am becoming more convinced that people see Whitey's Lindy Hoppers as a norm for "Lindy Hoppers". Recently I saw Norma Miller's book where she wrote that people saw the pros dancing rehearsed, choreographed routines at the Savoy, and mistakenly thought they were regular social dancers.
So, Murray taught simple steps to beginners, as did just about any one who wrote about it while swing was happening. And most contemporary materials I've seen pretty much try to dissuade people from learning "tricks" before they've actually learned to dance.
LA dancers who danced shag, "jitterbuggers" (when you start comparing usage of "jitterbug" vs "Lindy Hop", you will find that "Lindy Hop" was relatively rare in the 30s and 40s, based on usage in the popular media) also had a bunch of tricks that they used to win contests, and eventually end up on film, too. They were not normal dancers, either.
So, I don't know, I look at the Arthur Murray people dancing on their show, and think, if you took enough lessons from Murray teachers ...
I'm beginning to think Murray has gotten a bad rap, just because he taught beginners.
(I don't think there are any WLH original instruction materials for beginners. You had to be cream of the crop to be asked to dance with Whitey's crew, or even hang around them at the Savoy.)