To answer the question of who within an organization pushed to prioritize it: Users, lots of them. I've worked on few big apps and sites that needed to adopt d

To answer the question of who within an organization pushed to prioritize it: Users, lots of them. I've worked on few big apps and sites that needed to adopt dark mode, and even before browsers and operating systems implemented preferences for dark mode, it wasn't an uncommon feature request from users to completely redesign the apps/sites to be dark, even if that meant replacing the light color scheme. Once browsers implemented prefers-color-scheme, we got lots of requests every day months until we implemented dark mode. Project managers had to prioritize it because it was in such demand. There's lots of research that dark text on a light background is easier to read, but I suspect it differs by individual. I've always had a much easier time with light text on a dark background. Light tends to bleed at the edges for me, so light backgrounds make dark text look thin, while dark backgrounds make light text look bold, much easier to recognize. From reading a lot of the user requests, I'm not alone. For various reasons, lots of people have an easier time reading light-on-dark. An interesting related question for me is, when did dark modes start becoming so unusual? Sure, they were never universal, but there were quite a few sites in the late 1990s that would have a dark mode link that would set a cookie that would swap out the CSS for dark mode. There were even a few sites that would flip over to dark mode at night. It wasn't used for large corporate sites, but there were also apps that allowed user skinning, and I suspect dark mode sites started to disappear around the same time app skinning did.