How many times have I not sat at an art class with only access to the primary colors, being told that you could mix any color with them? The green never became green and the black always turned into brown. But with some kind of magic that obviously never reached me, I was supposed to mix a good green with yellow and blue. Everybody knows you get green when blue and yellow meet, yet I never succeeded in practice to get the grass any greener than military-olive.
If you struggle with the same issue I can tell you: it is a myth. It is nothing magical with yellow, cyan and magenta. You can’t mix them into every color there is.
It is three colors that can be blend into almost any color. But the truth is that you can buy any tube of paint you feel you need with conscience; you are not wasting your money.
It's thanks to Isaac Newton and his experiments with prisms that we got this long lived dogma about yellow, blue and red. At his time it was also believed you could create gold. There was also a constant search for some form of divine influence in the world, like things should be in groups of three or four (as two opposing pairs).
It is interesting that many today still take this myth for truth when guys like Rembrandt and Arcimboldo probably could have told you differently.
Thank you Legatus Mensae for the inspiration