No, I don't buy the green screen argument, any more than the randomness of paper being somewhat white and ink being in contrast to that. Certainly white on black is useful in astronomy, the stuff you are interested in is lit. This article was such a wall of text, I don't know if it ever supported its conclusion very well, which is ironic for an article promoting "productivity".
Not sure what this even means, sarcasm or not.
If the sun could be set in "low brightness", like a screen can (and ignoring infrared), then yes, you _could_ stare in the sun.