Member 2857 says:
Why do slalom racers have a narrow stance and downhill racers a wider stance then?
I answer that skiing flushes in slalom (vs. GS) involves more knee angulation, and in skiing flushes, there is an advantage to narrowing your stance. That having been said, if you take a race clinic with both (A) top junior racers and top-ten Nor Am racers like Mike Tichy, and (B) old school Masters racers in their 60s at the same clinic, the new school racers have wider stances, even though we're all skiing slalom. When not skiing flushes, the top World Cup slalom racers have a reasonably wide stance to generate the big edge angles, as someone noted above.
A slightly wider stance (and a slightly more two footed skiing) promotes better lateral balance, in slalom, which (IMHO and painfully learned experience) also makes fore-and-aft balance easier on short skis where getting the weight aggressively forward at turn initiation is critical. (And, for racers, unlike recreational skiers or PSIA 3 instructors, getting weight forward, leveraging against both front boot cuffs at turn initiation really is essential, no kidding, and it's _not_ about "weighting the whole foot" like good, balanced recreational skiing. I do regular balance training every week, getting forward is my priority in slalom racing, and I'm still not forward enough when the course gets steep. Sigh. The more I do slalom the more that it's clear my calling is really Super G.)