An excellent and concise explanation.

Allow me to add:

Average shooters and shooters not thoroughly familiar with understanding, acquiring, and retaining a correct "sight picture" for the particular sighting/aiming method throughout the shot; visual, unconscious, and subconscious sighting errors can occur that can cause the shooter to miss the mark, or completely miss the target or game, if they bring the POA into sharp focus and visually and mentally concentrate on the POA.

One common sighting phenomenon that often happens with some average and unskilled shooters that sharply focus on a "spot" on live game, especially large game, is they become so psychologically wrapped up in clearly seeing the animal -especially when their heart is wildly pumping, they will actually stop seeing and referencing the pin. They will unconsciously and totally cease using the sight(s) and end up just pointing the arrow in the direction of the animal and pulling the pin. Ever have a post-shot situation, whether you hit or miss the game, where upon critiquing your shot you cannot clearly recall your sighting process or seeing the pin throughout the shot?

Another sighting error that can occur for some shooters that focus on the spot, is a (visual) sight alignment error that can easily occur as they intently concentrate and focus on the POA. Although they are aware of their (fuzzy) sight pin, they do not realize that they have unconsciously shifted out of the path of their eye to target what their subconscious has perceived to be obstructing a clear view of the spot or the entire animal. This phenomenon results in the shooter being mentally tricked into visually believing their sight alignment is correct, when in fact their pin is being referenced on the spot too high or low, or too far right or left, or all of the above.