It's not to reduce light pollution, it's to have all the light pollution be in an exceptionally narrow band that the observatory can then filter out. The reaso

It's not to reduce light pollution, it's to have all the light pollution be in an exceptionally narrow band that the observatory can then filter out. The reason LED lights are so terrible for astronomers is because although they require much less light to achieve the same visibility, the spectrum is very spread out across multiple peaks, with different manufacturers having different peaks.