Why do athletes in other sports like racquet sports, batting sports, and golf focus on the ball being struck with the implement instead of the ball target?
In dynamic racquet and batting sports, where the ball is moving, it is much more effective to focus on the moving ball (instead of where you want to send the ball) because you need to predict where the ball will be at the moment of contact and react very quickly. In pool, the CB is stationary so you know exactly where it will be at the moment of contact, and no fast reaction is required. Concerning golf, your gaze direction is very different for the target (looking along the desired line or landing zone down the fairway, or the cup or flag on the green) as compared to the ball (looking straight down). If you are looking at the target, you will not be able to accurately strike the ball with the club. This is analogous to elevated shots in pool like jump shots, where the gaze direction at the CB is very different from the gaze direction at the OB. With elevated pool shots, most people are more effective focusing on the CB during the final stroke, especially if the target ball is far down table. If you are looking at the OB during the stroke, you might not get an accurate hit on the CB, which is so critical with elevated shots, where even a tiny tip placement error can result in a miss.