I learned when I was young to have a number of checkpoints in my backswing that kept me in the right position on the way back and on the way forward. Here's another; As we age our muscles in our arms atrophy. One of the easiest ways to see this effect is to stand with your arms hanging down to your side and see how much further your thumbs hang inside when relaxed. It becomes especially bad when you then hang a bowling ball on that arm. Many people don't even notice but their thumb will rotate inside 90 degrees on the way back. If they then try to 'pull' from the top instead of 'swing' from the top, a fly-away elbow will begin the inevitable process of going around the ball. We think we can control the ball, but our muscles aren't what they were and even 13 pounds can make the hand go around instead inside out.
Why is everyone pulling from the top? They want more speed. As we age speed wanes, but not because of our arm-swing. Our speed wanes because of our footspeed. As we age we are less sure of our balance. To compensate, we go slower. The answer is strength but few of us are willing to do the necessary exercise to strengthen our legs, so we can be more balanced and increase our speed :-) Even for those who can, eventually, we all slow down. Accepting our limitations is another problem we have :-) I have many friends who whine about lane conditions because they are unwilling to admit to themselves they just aren't the bowler they once were.