If it helps, it’s because it is a really, really bad situation if the person’s pilot chute is unsecured inside of the plane. The pilot chute is a small chute that drags out your main parachute, and if it goes out the door it can be a terrible day for everyone involved. If it goes over the plane’s tail it can damage the control surface, ruining the pilot’s control; it can drag the skydiver out of the plane in an uncontrolled manner, leading to injury by hitting surfaces of the plane and possibly being entangled in the various lines; and the person can injure or cause more mayhem with the others still on the plane.

If the pilot chute isn’t securely tucked away in the plane, courtesy is to stomp on it and everyone works to restow it where it belongs, but if it is near the door or already being sucked out the door? We all agree that the safest thing is to get that person out of the plane as fast as possible.