>That too was known for ages, and still no light changing apps for it like flux
How is Joseph Programmer von Notasleepscientist supposed to know that a blue-light dimming filter is something that he might want before he sees the effect in action? I'll give some credit to f.lux for popularizing the idea, but once the idea is out there, there are only two ways you can implement it: postprocessing in software, or postprocessing in the CLUT. You wouldn't need to know anything about how f.lux works to come up with one of them yourself, once you are aware of the idea.
How is Joseph Programmer von Notasleepscientist supposed to know that a blue-light dimming filter is something that he might want before he sees the effect in action? I'll give some credit to f.lux for popularizing the idea, but once the idea is out there, there are only two ways you can implement it: postprocessing in software, or postprocessing in the CLUT. You wouldn't need to know anything about how f.lux works to come up with one of them yourself, once you are aware of the idea.