> dark mode is for people who set their screen brightness too high
There can be other valid perspectives than your own.
I don't think your brightness sentiment is universally shared by most people, hence the downvotes. I think this comes from one particular study that people just end up parroting, possibly via third-hand gossip.
While a sufficiently low-brightness screen might have some specific advantages to dark mode, I think the issue is more nuanced than that.
First, not everyone can set their brightness to an appropriate level.
If the user is prone to migraines or light sensitivity, light mode even at a low setting could trigger headaches.
Light mode also produces significantly more blue light, which can have health side-effects as well.
If you keep a white screen on at appropriately low brightness in a dark room, the relative difference between the screen and the surroundings is still massive. This creates pupil strain as the eye constantly adjusts. Dark mode aligns the screen's luminance closer to the room's, reducing this strain.
Dark backgrounds make colors pop more vibrantly and prevent the "washed-out" look that can happen when bright images sit on a white background. It can also reduce halos visible around bright objects in photography apps and make the UI less distracting.
For battery-powered/mobile devices, dark mode uses much less battery power on OLED screens.