The simplest hardware design is just running it at say 10% max in flashlight mode but allowing for short bursts of overdrive for flashing. The LED is big enough to handle short bursts, but not thermally cooled well enough to work at full power all the time. So you rely on firmware/software to do its job instead of having specialised hardware controller that's only job would be to make sure LED isn't on on 100% for more than say half a sec.
You control software so you don't GAF, but people putting custom one have to take same amount of care
Second example: You're an engineer and need to drive a backlight. You can
* slap a constant-current controller (buck or two of parts) so 100% is a maximum safe level all while regulating it at >90% efficiency * slap a high value resistor costing $0.01 so 100% is maximum level is safe but you lose a lot of power in the resistor * slap a low value resistor then just drive it at 20% duty cycle and waste less heat in resistor all while still costing $0.01
They just most likely picked 3rd. Or picked 1st and misengineered the limits I guess...