The highest color contrast = The most legible solution on screen?

As my earlier article said, black and white provide the highest contrast, and similar color paris such as white and yellow on black and blue background could produce the highest color contrast as well.

Is that mean it will determine the best choice for screen text reading?

Some public cases shows when a message or instruction involves a more complicated explanation, black and white provide the highest contrast this does not always provide the most legible solution. The book “about face” gives a obvious example to support this idea: British road signs using white (sans serif) lettering on a dark-green background; “hazard warning” signs where black letters are used on a yellow background.

Is it possible that the message or instruction on web involves a more complicated explanation?…
Therefore why do you believe it is safe to choose a black color type?