While I agree with you that a dark theme would be nice, this is fundamentally a manpower issue. Such a thing would need to be implemented first in the repo running this webpage, which is based on karax.
I assume this forum wasn't set up with CSS or SCSS properties in the first place, so it would also entail first identifying all the places where colors were used, replacing them with CSS properties and then creating a second set of colors for those properties. And then implementing a mechanism to toggle between those. Certainly not insanely difficult by any means, but it would eat time.
