This sounds like an opinion, not one backed by evidence. “A 2017 study in the journal Applied Ergonomics found that “dark characters on light background lead to better legibility and are strongly recommended independent of observer’s age.” And Human Factors: The Journal of the Human Factors and Ergonomics Society found in 2013 that “the typically higher luminance of positive polarity displays leads to an improved perception of detail.”

Raluca Budiu, the NNG’s Research Director says “they generally don’t recommend dark mode for “normal vision users,” and says positive contrast polarity, aka good old black-on-white text, is “easier to read and more glanceable,” especially in low light conditions. Dark mode could be useful for little scannable chunks of data, not great for reading lots of white text on black background. (Even worse is a poorly executed, non-user controllable dark mode such as in Pixelmator; I literally cannot read the medium gray interface labels on the black background).

In addition, from what I’ve read, dark mode doesn’t save battery life on LCD screens.

My request to all UI designers out there: PLEASE give users the option to opt out of dark mode. And make sure that even in light mode, you test readability with users other than young, sharp-eyed designers ;-)