Originally Posted by hellside
From what I can tell, HeluvaSkier isn’t even a student of the other system. ..
To be as charitable as possible, I'm going to just assume you are very naive.
As far as dynamic movement skills, and how someone can look good on mellow groomers and be fated to be in one of the lower groups if they take, say, a bump lesson, it relates to the demands of mellow groomers. They are smooth, consistent, generally wide, etc. Pow runs that work well for intermediates also share those characteristics. Take that groomer and simply bend it into a U, i.e. a halfpipe, and all of a sudden you need different movement skills because the environment throws more at you (and high edge angles actually become a technique problem, as well as a bit of a social don't-do). A blind person can ski either mellow groomers or a halfpipe, because both are pretty predictable, but the halfpipe is much harder.
It does go both ways, some of the best and most active bc skiers don't look real good on mellow groomers, though they've developed movements that work very well for what they do. To the extent that they spray, it tends to be about very different things, and someone spraying about their mellow groomer freeskiing they'd find hilarious. But, they ski in a very dynamic environment, that could scare the best racers, and often use very dynamic movements.
In general, the more dynamic your environment, the less feedback you want from things like your skis, as well, which is why frontside carvers are good for frontside carving, but unfun for other things.
JASP's point about polishing down gross motor movements raises an interesting question. Does the polishing happen, generally, in a linear fashion, or would it be more of what the college kids call a step function? My anecdotal, completely unscientific opinion is that even for adults it's more of a step function, most of the time. Haven't seen that studied in the context of skiing, though.