a public service announcement
I still don’t understand why none of my art teachers ever told us this.
I’m just going to point something out for anyone who is confused. There’s a big difference between “primary colors” and “primary pigment colors”.
The primary colors, as far as our eyes are concerned with regards to light, are R/G/B, as part of the additive color system. That’s why televisions use Red, Green, and Blue pixels.
When mixing pigments/dyes/ink, like with printers, CMYK is used, often referred to as the subtractive color system (K standing for black, because the pigments when mixed usually make a dark brown).
RYB is an older version of of the subtractive system, due to access of pigmets at the time, lack of understanding of how light works, and the fact that it is still a pretty usable system. It was eventually found to be ineffective when it comes to producing all colors, but it still produced a good portion of colors to the point that it was generally accepted as a standard. It does still serve as a good way to teach kids the basics of mixing colors.
So that’s why you may be confused why art classes didn’t teach you this. RYB is that classical color wheel, CMYK is the modern equivalent after studying light and applying it when making ink/pigment. These are the primary pigment colors that are generally accepted as correct.