NM Game & Fish doesn't want to give up the revenue from license sales, so they want to reduce the success rate. It isn't scope technology that has increased the success rate, it is primers, powders, inlines, and quality barrels. They could have outlawed guns without exposed hammers without discrimnating against older hunters. But, that would have made rifle manufacturer's mad, and they have some political clout.
One reason for the success of the muzzleloader season, is it is usually prior to the rifle hunt. Sometimes the poor animals are surprised that it is hunting season. It is clearly a fact that there are more animals in the woods before the hunt than after, so muzzleloader hunters get more opportunities by hunting first.