A handrail is a fall-arrest device that only works if the hand can stay on it through the whole descent. The most dangerous moments on a stair are the first step down, when the user commits their weight, and the last step, when they expect the floor and may be a tread short. A rail that stops before the bottom tread releases the user's hand at exactly the second of those moments. That is why continuity over the full flight is the requirement — not the presence of a rail somewhere along the stairs. The inspector reports the discontinuity as a safety item, and continuity sits alongside height, graspable profile and secure attachment as the standard checks on any stairway.