The point is that if you're driving with your headlights on, even in the middle of nowhere, in pitch black and no other cars around you, you do not have any night vision.Any light entering the eye constricts the pupil and somewhat "resets" the eye(s) adaptation period to regain full night vision (roughly 30 minutes). It doesn't matter how a light source enters the eye (reflected or direct), they have the same outcome of degrading your vision and reducing the sensitivity to light.
Why are people even mentioning this is strange.