I get the sense that was written by a younger person who didn’t grow up with black & white TV, black print on (slightly yellowed) white paper, and monochrome monitors.
It does help with focus though. One of the early programs I wrote on a full-color PC was to adjust the OS palette to emulate a monochrome amber monitor. Very easy on the eyes, less distraction, great if you’re spending hours reading/writing text and need to focus on creativity. I still have my colors set that way in Writemonkey. F.lux’s ‘Himalayan Salt Lamp’ setting isn’t bad but not quite the same.
