[barrowclift]

Not necessarily true, I'd argue the "perfect" dark mode uses the system's theme by default like you said, but still allows visitors to manually set light or dark should they wish to view the site a particular way (perhaps they prefer the light mode, etc.)

[asiachick]

Agreed. S.O. recently added dark mode and for some reason my eyes couldn't focus on it. No idea why. I run my editors and my terminal in dark themes. Maybe they didn't have enough contrast. Maybe the fonts are too small or too thin. I have my browser set to "prefer dark mode" but I'm really happy S.O. let me opt out.

[WiseWeasel]

I think the only reason someone who likes dark theme would opt out of your dark mode is because it's not as nice/readable as your light theme, or vice-versa. You should fix that instead. Once your dark mode support is perfect, or at least as good as your light theme, then the toggle serves no purpose.