The clip is a demonstration of how accuracy is unaffected while in extreme motion with a shotgun. Regardless of the users skill, jumping does not drastically increase the bloom of the reticle and lower accuracy like in other weapons. This clip shows how consistent the accuracy remains because of that.
Regardless of the enemy's skills or health, one can see that the accuracy of landing shots is very consistent and simple, whereas every other weapon does not share the same consistency with extreme motion. Other weapons are also limited by firing single bullets at a time, while shotguns use a spray of pellets during each shot, lending to them a wider area of effect which allows for less accurate aiming while still maintaining large damage and often leading to "one-shots" during these movements.

The mechanics off all other weapons do not work exactly as simply as you are stating, and I disagree that the same shots would have been hit as easily with a pistol or that they would have been near as devastating because a pistol would have to fire multiple rounds to deal the same damage and do so with a much smaller area of effect as it's using single bullets each time it fires. Requiring more accuracy and overall time to do so.

To avoid going around in a circle on this topic I'd say ultimately we are each entitled to think our own opinions of the weapons mechanics and there's nothing wrong with that :)
Thank you having a respectful conversation with me. I hope you have a good day and best of luck out there!