To me, the number one thing that leads to more super top end bucks is simply not shooting 1 1/2 year old bucks. Now there are many other things that can also be done to further the chance that a buck goes "mega", but I say if that buck can get through his first fall with antlers then it's a numbers game from there.
More guys are passing on more young bucks and then combine greatly improved nutrition, at least in certain areas, via foodplots, etc, and holding back some land as sanctuary and there are more of these super bucks out there. I bow hunted deer for quite a few years before I even saw anything close to 150", let alone over 200". Back in the late 80's where I was hunting most EVERY buck would get whacked by EVERY hunter that I knew that had a chance at him. 20 or more does could walk by unscathed, but the first raghorn down the trail got it.
Sometime in the early to mid 90's I took a fair amount of ribbing from guys I knew when I told them I passed up a shot at a buck, albeit a forgettable 6 pointer or something. They really did not believe I didn't shoot, etc. Now all of these guys and all of those properties are under some form of management or self regulation and every year there are 2-5 135"'ish on up bucks seen in the area every year.