I never understood what the fuck was up with that. Most older dumb phones had that feature and even if they deemed it unnecessary, the sheer amount of flashlight apps would prove them wrong
Older flash bulbs weren't really made for long uptime. If you were using your flashlight for under a minute looking for something it was fine but any longer than that and it would start getting really hot. Once manufacturers caught on that everyone was using apps for it (and potentially damaging their phone in the process due to heat) we got better bulbs and baked in controls for it.
If only running more flashlight apps made the flashlight brighter and brighter.
"I've used the entire capacity of my phone to simulate the light of the sun. Please be sure to wear sunglasses and apply sunscreen before I turn it on."