If we could dig in enough and interview skiers they might be able to
give us these missing datapoints. Even video might show it, if anyone
cared. That is, I suspect that top skiers have indeed tried various
other methods (based on their own initiative, coaching, imitation,
whatever), even for a decently long time, and found them lacking so we
still end up with this variety of style in top finishers. So that you
might be able to get info on a particular skier using a wide variety
of styles themselves.

It would be good to find the common traits. But are you sure about the
ones you list? Offhand, the "quiet upper body" one might conflict with
a comparison that Harvey made between champs who stayed low and those
who rose up and crashed down---that sounds like more "bobbing."

Technique is a freaky thing. I had brief periods in 2 sports where I
got pretty good---in both cases technique became more important yet
"doing it my way" also became dominant, not only that but as I became
fitter "my way" acquired a wider range. It got more particular and
general at the same time. It was fun! I suppose it's important to keep
trying, testing, measuring.