Why were massive antlers easier to grow 15,000 years ago?

Many a deer hunter has had dreams, day and night, about being on stand when in the distance the antler tips from a huge buck come into view. The internal program shifts to “don’t look at the antlers, pick a spot and make a good shot.”
Of course, if this were easy, no one would ever have buck fever. For many of us, it actually doesn’t take much to get the heart pumping and through-the-roof adrenalin levels. Heck, happens to me when a doe comes into range. But, what if we lived 15,000 ago in country inhabited by the “Irish elk”?