Just about every encyclopedic reference I can find gives the color primaries as Red, Green, and Blue (for additive) and cyan, magenta, and yellow (for subtractive).

But I keep hearing about the primaries red, yellow, blue from authorities in the art field. What's more, both Albers and Itten talk about RYB, despite the fact that both wrote and worked well into the middle of the 20th Century, at which point, the CMY system should have been well-known.

Is there any reason why RYB is still around (apart from the psychological), or is it simply an obsolete approximation for CMY?