The most effective schools do similar things, and call it "outdoor education". It's expensive, and I doubt there's much evidence about the long-term effects on the students.

I'd guess they don't take it far enough to be useful. When people first experience cold, hunger, fear and exhaustion, most focus on their suffering, and feel helpless. You can learn to take the discomfort for granted, focus on your actions, and feel proud. That takes more experience and mentoring than the average student gets.

Also, being able to handle the normal stuff is good, but not caring about it at all is bad, and the middle ground can be hard to find. Tim Winton's novel, Breath, develops that idea.