earlylight

Two - four reasons for step ins: The reason climbers slept with their crampons on and got severe frost bite was because tying on your crampons, in the morning, might take more energy than you have, especially at high altitude, so they left them on. Sleeping bags had canvas lined bottoms so they wouldn't be sliced up. Step ins are faster, probably more securely attached than strap ons, and often they add rigidity to the boot.

Jim