I'm fine with going fast on a sled being a sport. That's cool. But, it seems like something where it's only valid if everybody involved is actively doing something on the way down, not just being ballast.

One person sledding makes sense. But, in this sport, the guy on the bottom can't possibly be anything but ballast, can he? He can't see anything, so he can't be steering or braking, right?

Same with bobsled, the guy at the front is steering. Maybe the people in the back help with something, but they can't be too actively involved because they can't see.