> Too much contrast has never been an issue, which is why no one uses flux or dark themes, right?
f.lux is for increasing color temperature. Dark themes are for reducing the ratio of bright to dark. Neither is primarily intended for reducing contrast.
> It's relatively easy, by turning #ffffff and #000000 both closer to #ff0000, or in other words, by reducing the contrast.
Yes, but decreasing contrast is an unfortunate side effect, not the goal. This is like saying that the purpose of a light bulb is to increase your electricity bill.
> Dark themes (excluding amoled themes) exist to reduce the perceived contrast between the screen and the environment.
Yes, but not the contrast between text and background.
f.lux is for increasing color temperature. Dark themes are for reducing the ratio of bright to dark. Neither is primarily intended for reducing contrast.