To be fair, both dark mode and light mode are bad. For me, optimal is with some dark grey background that mixes well with the surroundings around the screen. The point is, not to have contrast with surroundings. Kindle, or the text consoles on older CRT monitors looked good because they were not too bright against the surroundings.

And the content on the screen felt like real-world tangible object.

Having said that, I feel that dark mode (full dark) is a product of "new is exciting", "game theme", "dark means serious, mystery, suspense", "no glaring", "linux/console style, so geek", "we are coders, so different from normal people" etc

The reality is, full dark theme requires more brightness and more power consumption. It feels like searching for things in a dark room without light (mystery, suspense factor). Light theme can feel more relaxed, with lower brightness settings.