If that were so great, people would still be doing it, because they'd be winning over other riders who weren't. Think of racing as analogous to Natural Selection - that which gives advantage is propagated and overtakes the less advantageous. Also, looking at those guys in the Moser position makes my inflexible back ache. I have always been so inflexible that I cannot get closer than about mid-calf when trying to touch my toes. So I ride with a straight back and roll my pelvis. I can't do closed hip angle.
In a way, it reminds me of a recurring discussion I have with my wife. She's fascinated by the disinfectant properties of things like vinegar, which she reads our ancestors used to use for cleaning. I point out that 1) vinegar is a relatively poor disinfectant, 2) those ancestors didn't even have Germ Theory yet, and 3) infectious disease was one of the most popular ways to die back then. So, adopting the disinfectant of people who largely died of infectious disease may not be the wisest move.
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"Don't take life so serious-it ain't nohow permanent."
"Everybody's gotta be somewhere." - Eccles