Do people who use dark themes also not write very many comments, or perhaps just not pay much attention to them, such that they don't notice the abd contrast?
I don't use dark themes, but what I've noticed when looking at the screens of coworkers who do is that the gray text is much more readable on a black background than on a white one.
I don't really an opinion on this issue, personally, because I disable colorization entirely.
That's an idea I haven't heard in a long time! I remember seeing blog posts a long time ago where some people disabled colorization, but I haven't seen anyone doing it recently.
