Its not only Genetics and nutrition that play a major factor, but I think people are not taking into account hunting pressure....

there are some area's where most hunters are meat hunters, and shoot anything that is legal. If you have a high number of hunters, and esp people who shoot anything that walks in your area, bucks just don't have a chance to get to the 3.5yr + mark, and never hit their genetic potential. Unless you have exclusive rights to hundreds and hundreds, or even thousands of acres of land, all the QDM you want to practice will never amount to anything in the way of older bucks. Not everyone has a big buck on their property, so holding out and waiting, may just discourage them, after yrs of not seeing a "shooter" buck.