you are thinking of projectors... those have cutoff, and they just happen to be LED's.exactly why a LED globe with no beam cutoff creates a blinding haze to oncoming drivers...H4 reflectors are designed for H4 halogen globes only with the cutoff built into the reflector, hunt around and there are LED's with cutoffs that work just fine beam pattern wise.... yeah, PITA with most things being illegal but the main ones are worth being that way......
Halogen bulbs do not have cut off. it's all based on the reflectors. The nice LED replacement bulbs approximate the halogen filament. The reflectors don't care what produces the light, just that it produces the light in the same location and direction as a halogen filament.
As long as you are happy with all your rules