Eliminate use of rifles?
Better yet. Put trigger locks on guns that work like ignition locks the drunks have to get in their cars. Lots of deer walk.
That's all the rule was designed to do, and it was successful in that. I would argue that it would have increased mature deer(3-7), but likely a minor or negligible increase. Any time you get deer 1 year closer, you'll have a few more in the upper rungs as well. Young bucks are stupid and easy to shoot. Anything you can do to give them an extra year or two will help educate them a little more and make them a more wary target as they age.