Were they to do so, few would buy them, since they all want halogen searchlights with a minimum of 150 watts.
I'm not often on the river at night, but can remember a number of occasions when I have had the dubious benefit of a spot light shone directly at me, effectively blinding me.
On one occasion I was going down Upton Dyke. Anybody who knows that narrow channel will be aware that passing another craft in broad daylight requires some care and observation.....