Hunters would prefer to hunt by daylight, for the most part. If light-hunting at night were allowed, that would be the only way to take the best game, because as the comment you're responding to notes, it's much easier.
So everyone would be forced to do the thing they don't want to do, if they want to take a deer at all. That's a bad equilibrium, what we call "not sporting".
Not trying to be a jerk, believe me, but try it some time. Deer have this mysterious ability to f*cking vanish during hunting season. In one town I lived in 3M had a plant with a little pond that was fenced off. During deer season all the deer would hop the fence and hang out at the factory because they knew nobody was allowed to hunt there. It was hilarious.
Hunters would prefer to hunt by daylight, for the most part. If light-hunting at night were allowed, that would be the only way to take the best game, because as the comment you're responding to notes, it's much easier.
So everyone would be forced to do the thing they don't want to do, if they want to take a deer at all. That's a bad equilibrium, what we call "not sporting".