Cell phones are well and good for finding something you dropped in the theater, but that's about it.
1. I don't have a smart phone, but most of the people I know who do (virtually everyone) complains about poor battery life. I can't replace my phone battery under any circumstances where I would want a flashlight, while the flashlight I have has six spare batteries in the same shoulder bag as the flashlight. Multitasking means the phone battery is more likely to be low at any given point.
2. The phone flashlight is much harder to access. You have to unlock your phone, find the app, and turn it on. Then you have a device that functions as a not-very-ergonomic flashlight with an effective range of only a few feet. Whereas my Fenix has a tailcap on/off click switch and has an effective range of several hundred feet.
3. A flashlight is mechanically and electronically extremely simple, and good ones are not prone to malfunction or breakage, whereas under rugged conditions a smart phone is likely to get stupid quickly.
4. Having a powerful flashlight on hand when it is needed makes you look
cool and
prepared, whereas hunting around for something on your hands and knees on the floor in the dark using your cell phone as a flashlight makes you look like a
doofus. No one wants to look like a doofus.
