I want a dark mode switch in my browser so badly
The reason is Apple no longer offer a non-super-glare screen on their laptops any more. I bought an MBP about 10 years ago, and the choice between a "matte" screen or "make everything more difficult to see in every environmental condition except inside the Apple Store" screen. Obviously I went for matte.
In their infinite marketing wisdom, Apple has removed the matte option.
Eventually I decided that I preferred that the theme match the ambient lighting conditions. The recent operating system and browser features to provide adaptive behaviour is exactly what I sought. I now use light themes during the day–I am also a fan of natural light, and dark themes at night with reduced blue and lower colour saturation. I personally don't understand the preference for dark themes in bright ambient lighting. For me it seems to induce more eyestrain than relieving it.