Anything they have to look at to get informed is a huge burden. Anything that burns up batteries driving a display is a huge burden. Anything that destroys ni

Anything they have to look at to get informed is a huge burden. Anything that burns up batteries driving a display is a huge burden. Anything that destroys night vision is a huge burden. So, anything that provides them the most essential bits of combat information (e.g. that is the direction back to base) without need to look at it, and using only microwatts, is a huge benefit.