Actually it's quite easy for newbies, who are often to be found on such dive boats, to confuse them. And that bright xenon appears as a weak blinking light if you are far enough away or viz is low. The boat does not want some inexperienced diver needing to get back to the line to chase down a blinking light only to realize it was another diver and the line is nowhere near. Or to drift further from the line than they planned because they saw a blinking something in their peripheral vision and assumed they were staying in the area of the line when they were actually moving away from it with another dive team.
I'm just pointing out some boats (like the ones that do Flower Gardens) have a no-blinking lights rule. You can argue that it's ridiculous all you want but you won't be using one on a night dive on their boats.
