>we've fallen so far behind in control over our UIs that "dark mode" is legitimately considered a feature

In case people don't believe this, there was an update for Office THIS WEEK for Outlook to support Dark Mode on OSX Mojave.

In 1995 there were far fewer platforms than there are now, and most people only had one: their own computer.

Nowadays, we expect the same services to work on our laptop, our work computer, our personal iPhone, our work Android, our smart TV... the importance of parity between versions is much higher.

True, and also, the fact that apps have to work everywhere because everyone’s either on Mac, Windows, Linux, or BSD. And also a lot of power users and people who except things to just work compared to the early days of the PC. Remember sound drivers?

I don’t quite understand your point. macOS just recently enabled dark mode as a “feature” pretty much decades after other OSes have had this built-in

To me, dark mode is the prime example of the flimsiness of relying on native GUI solutions...for years Apple ignored users and apps that wanted dark guis, despite the fact that dark mode is legitimately a lot better for a lot of people

Try leaving the Apple bubble. Windows 95 had completely tunable color schemes and fonts. Even Windows 3 was highly configurable. That configurability went away with the rise of the web and the death of native GUIs, to the point that Microsoft didn't even bother making the native toolkit configurable at all in Aero.

We could tune up our own universally applied dark mode in 95 quite simply, but now each application has to implement that itself.