Other forms of pollution are worse, but light pollution does harm animals. When baby turtles hatch they instinctively look for bright lights lower on the horizon and go towards it. Because naturally, that will be the moon reflecting off the ocean. Bright beachfront buildings are even brighter than the reflection of the moon leading them to wander away from the ocean

Moths and frogs are also attracted to lights. Migratory birds rely on seasonal cues such as changes in the amount of light. The OP article also mentions in the intro that it is reducing bat populations in areas.