Then again, I also find it funny that "dark mode" is heralded as something revolutionary, when long ago people could customise UIs far more. You can still do that with userstyles, another thing that seems to have gotten mostly ignored these days...
As to UI customization, often that was an inconvenient cop out not a great enabler. "We don't want to figure this out so just change things yourself, but then you'll switch PCs or reinstall and you'll lose all of those customizations and you'll never do it again and you will forever leave everything vanilla".
Is it worth websites making a big deal about? No, not really... At most it should put a little badge when it detects the dark mode CSS allowing unwilling users to disable it, but it doesn't seem like something that gets dragged on as long as it has by a couple of sites.
The vaunted Apple UI was the exception, forcing an inverse color scheme on all users, all the time. They refused to admit the failure of the "screen as a piece of paper" analogy that ascended during the "desktop publishing" rage of the late '80s/early '90s.
So now Microsoft inexplicably REMOVED user-definable color schemes from Windows (around the time of Vista, I think), and Apple has clumsily implemented a hard-coded "dark mode." If you're a developer, you know how hideously broken numerous Apple UI controls are now as a result (rendering nearly invisible text and arbitrary background colors).
You could spot Web designers and even design tools that didn't know what they were doing when you'd pull up a Web site to find it mostly blank. This meant that the page overrode your system's dark background color with white, but didn't override your white text color. The result, of course, was white text on a white background.
Google embarrassingly introduced this defect into the Google News page at some point, rendering all the story abstracts invisible.
Good times.
Hm. I like the "better" one more. However, it's cheating -- the first screenshot displays a lot of white text in the filters and the text of the questions. The text of the questions is most of what I find off-putting about the first screenshot.
The second screenshot displays no white text at all. The filters menu isn't visible. The text of the questions isn't visible. Text that's gray in the second screenshot is also gray in the first screenshot.
What kind of comparison is this?
For an accurate comparison, compare the first and last screenshots in the article.
It looks like they're using the darkest background ("pure" black or nearly so) for code blocks. Seems like a reasonable choice to me, given that the need for clarity is strongest there.
The important part is that you could change it relatively easily if you didn't like it, but the "modern" trend has been to remove that ability.
That and everyone patting themselves on the back for building dark mode.