Even factory LED headlights can be blinding if the road isn't flat. At some point, however, you'll reach a point where you hit the beam cutoff, so perhaps as you get closer to them, you simply hit the cutoff point such that they are no longer blinding?

Just playing devil's advocate, because I see way too many people either with high beams on when they shouldn't be on (some cars have different bulbs for high beams, so it is really easy to tell on some cars), or no headlights at all despite it being dark out. Funny enough I ran into both situations today, and they were both Honda Civics.