Being a skeptic, I’m pretty sure the whole narrow wide thing might just be there as a mechanism for selling more expensive components.
I bought a Cannondale cross bike many years ago that was equipped with SRAM 1 x 11 Force but the chainset was Cannondale’s own with an FSA Megatooth (if memory serves me) chainring that only had tall teeth, rather than the alternating narrow wide setup we see everywhere now. I don’t remember dropping my chain with that one although it’s impossible to disengage the clutch on a SRAM rear mech so hard to say if it was as effective.
Shimano’s original XTR 1 x 11 chainrings also did not have the narrow wide profile. I can’t recall when they changed that though or for what reason.
I think the difference in efficiency in the 1x vs 2x test probably actually come down to the difference in efficiency between SRAM and Shimano chains. Would be great if they re-did the test in a way that this wasn’t an issue.
Mike