> That's just about caring or differentiating about relatively small difference.
Which this is all about! The author talks about 51 Munsell color samples out of 1500, so only 3% of the gamut.
Look how specific "violet" is in the Munsell system: https://munsell.com/color-blog/munsell-book-of-color-1929-tr... (violet is at #17).