The part of the lens that produces the upswept part of the lowbeam projects the light diagonally upwards, while the other part of the lowbeam is spread horizontally, with the horizontal cutoff (you can see this from the orientation of the flutings of the lens).

This means that if you use the vacuum adjusters to not blind oncoming traffic with the upswept part of the beam, your horizontal cutoff will be too low to be useful.