I strongly suspect this is an example of a desirable disfluency. If you make things harder to visually distinguish, your brain takes in the information better because the parts that need to work harder influence attention.

I also disable most highlighting. I find it terribly distracting when coding or doing other menial stuff, my exceptions are greping or diffing, but those only use 1-2 colors

By looking at it? Every time I see a screenshot of someone's super fancy color scheme it looks cacophonous.