Seems pretty obvious to me that blue is the color that gives best contrast to a white background, while not being black or being so dark a color that the hue do

Seems pretty obvious to me that blue is the color that gives best contrast to a white background, while not being black or being so dark a color that the hue doesn't stand out. This is why blue pens are considered the only acceptable pen for writing (such as filling in a form, or a school paper) other than black. Similar to the reason to use yellow for highlighter and otherwise for changing the background color, you want a light color whose hue is detectable, but it similar enough to the white background that text is still easy to read. The Munsell color solid is distorted to show that pure yellow is light, pure blue is dark. https://art-design-glossary.musabi.ac.jp/wpwp/wp-content/uploads/2014/09/228_color-solid_01.jpg https://art-design-glossary.musabi.ac.jp/wpwp/wp-content/upl...