I think the poster was talking about phrasing, “dark mode” implies there are modes to switch. The article seems to incorrectly be conflating dark mode vs dark themes. Dark themes tend to be unadjustable.

IMHO I usually just flip to the reader mode on my phone browser or desktop browser when I don’t like the theme of a website. This obviously doesn’t work for all websites but it’s a nice work around since most reader modes allow you to adjust coloring yourself.