system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how can my cellphone flashlight damage some art piece while their always on 100 W halogen laps pointed right at the painting don’t do anything?
gpt
Cell phone flashes which are glorified LEDs probably aren't that damaging, but the rule of "no flash photography" originated from a prohibition against true camera flashes. Those flashes are very powerful, to the extent of if you colored a piece of paper with a black sharpie and flashed it point blank you could start a fire!

Establishing that rule makes a lot of sense because those kinds of flash will indeed cause more damage over time than the 100 watt halogen lamp. The museum doesn't want to try to bother explaining the difference between different kinds of flashes or trying to draw a sensible line between damaging flashes and those which are probably safe, so the ban is universal. Besides, the 100 watt halogen lamp is probably enough that you don't need a flash anyway.