Another problem with this was that some software was just broken. For some reason, some devs explicitly set the text color of labels in their software to black

Another problem with this was that some software was just broken. For some reason, some devs explicitly set the text color of labels in their software to black instead of the system default color, but left everything else—including the background—to use the system's color. So you end up with black on black for your dark theme.