Where legal, marksmen can indeed fix their aimpoint on the turkey's head, the way most of us do with tightly choked shotguns. This way you either down the turkey directly with a punch to its walnut-sized brainpan, or you miss. It's a small, but sure target.
Those riflemen who choose to shoot the wing butt often find that the turkey will run, fly, and sail away, only most likely to die later, and out of reach—especially if it hits the bird just slightly off the mark. A spine shot will anchor the bird, but a near miss surely won't. There's little room for error either way.