If all shots at deer in SC were in broad daylight, I'd really not even bother with a scope; a good aperture sight is all I'd want. Unfortunately, the whitetails seem most active in low light conditions, so . . .
If I were "on safari," a long way from home, having spent a considerable sum to hunt Alsakan or African game, I'd not only want iron sights as back-up to the scope, I'd want a second rifle as back-up to my primary! As a typical hunting trip for me is approx. 15 - 20 miles via road, then a 20-30 minute hike to my hunting area, if I suffer a scope malfunction, big deal! I'll mutter, go home, rectify the problem, and return to the field after all's been fixed.