Because it’s not just about color temperature, which is a superficial metric. It involves light spectrum, flicker rate, so forth. LED’s in the conventional sense offer isolated blue light, which is very damaging to a circadian system that evolved for full spectrum sunlight during the day and darkness at night. This gives you one example of the harms involved with the eyes

Isolated Blue Light Is Quietly Damaging Your Eyes: Here’s Why (and How to Fix It)

How isolated blue light disrupts your retina, circadian system, and long term eye health.