I was not aware of how much of an accessibility issue having only a dark colour scheme posed. I know there are preferences but seeing the replies on Nai's Mastodon post about the difficulty of reading white text on a dark background for some with astigmatism was surprising.
But there are some people (like me) who may be visually impaired. Astigmatism, for example, can make reading text that is white on dark a real PITA. An effect known as "halation" occurs, where each letter behaves as if it were a flashlight, gaining its own halo of light and making all text read more blurry than normal.
No matter how good your glasses are, astigmatism still causes you to see a little blurry—it's something you get used to. But this damn effect makes all the text read as if you don't have your glasses on, or even worse, leading to much more tired eyes or even pain.
Linked in the thread is a Vice article in which the author also shares similar difficulty reading dark colour schemes with astigmatism but also why dark backgrounds work for others.
Read from linkMy own very-astigmatic eyes are exhausted by dark mode, but for many others, dark themes are an accessibility benefit. White backgrounds emphasize floaters, those tiny spots of fibers that appear in some people’s vision. People with disorders like photophobia or keratoconus, conditions that cause high sensitivity to light, might read more easily with dark themes.