Good point Okiaros,

QDMA is not about the racks, it is about restoring deer herds to a 2-1 doe buck ratio or better. 1-1 is best, but often impossible, and as QDMA seeks to balance hunter satisfaction, 2-1 or better is the goal.

If you aren't shooting every buck you see and passing on every doe you see (as a lot of people were taught to hunt) it will change your deer herd for the better - as you said better age and social structure. That in turn will probably lead to more mature age bucks who happen to have bigger racks. It does not change the genetics of your herd, but works to maximize the genetic potential of your herd.