That being said, it's hard to argue that Apple (or Android) shouldn't be able to set boundaries on behaviors which are only allowed to be done by the OS as a opposed to an app. Apple's tight control of device screen characteristics makes it pretty understandable that they don't want one app able to control how another app looks on the screen.

The optics of the f.lux situation is just really, really bad. But considering the f.lux never really charged, they have a claim to fame that few can match: creating a feature good enough that Apple incorporated into both iOS and MacOS (now in beta).