I get headaches if I read white text on a dark background for too long, and my understanding is that about half of the population of the planet has astigmatism to some degree or other
i like the way dark mode looks but if i use it too long it gets physically painful in the form of headaches, i generally don't use apps that only have dark modes as a result, unless i can make a custom theme for it, then i will more often than not make a light theme for it. or i'll make a theme that automatically updates the colors based on what i choose in my system settings, which is something i've done for Lemmy and a few other things, but yeah
Doesn't look like the laptop they tested, the Asus ZenBook 13 UX333FA, uses OLED. So yeah it isn't gonna make a difference since you're still lighting the full backlight. But it makes even more of a difference on phones, since their processor is less powerful by comparison.