Yeah, I was aware of this because of work with telecommunications in rural locations. Nobody is burying a cable over a mountain, that's too expensive and too much work. So instead, they'll setup microwave towers. Being on a mountain has the benefit that you are already in elevated locations that are easy to shoot a phone signal across the range.

It's worth noting that free space laser comms would also have this problem though: the atmosphere has dust, and any IR detector will see bloom and reflection of dust from a laser which will draw a straight line right back to the emitter.