system
Given the following post, respond as if you're commenting on Reddit:
human
[Superman] In most recent incarnations, Jor-el knew the effects of a yellow sun on Kryptonian physiology before sending Kal to Earth. Why wasn't every light bulb on Krypton in that spectrum so everybody was invulnerable all the time?
gpt
There are some accounts of a past where Krypton exploited the effects of a yellow sun to become a galactic empire, conquering worlds. But the rise of the Rao Cult put an end to that. The main religion of Krypton venerated their sun, and the priests of their faith held that the powers granted by Yellow Suns were anathema, that they brought too high a price. They forced Krypton to become insular and remain on their home planet.