What I was taught (back in the days when everyone was taught to use a tourniquet) even then was that you use a tourniquet only in cases where the limb is lost anyway. If you have to use a tourniquet, you've already sacrificed the limb. In other words, it's used only to keep someone from bleeding to death when everything else has been tried and it's a case of it being better to lose the limb than the life.

The reason tourniquets are no longer recommended for civilian first aid use is that far too many people were losing limbs unnecessarily due unnecessary use of tourniquets. For the military, or any other case where the limb is completely mangled and there's severe arterial bleeding, it's a bit different. But once a tourniquet is applied, the limb is gone! Out in the wilderness, there is absolutely no way you are going to get the victim to a hospital in less than an hour!