The reason why I call RGB "wrong" is because the L and M cones both have peak sensitivities to greenish light. So the three cones would be something like "yell

The reason why I call RGB "wrong" is because the L and M cones both have peak sensitivities to greenish light. So the three cones would be something like "yellowish green" (564-580 nm), "bluish green" (534-545 nm), and "violet" (420-440 nm). It is a common misconception that long cones are mostly sensitive to red. People often say that, but it would be more accurate to say that long and medium cones are both mostly sensitive to green light. At least two cones are usually stimulated, and often all three, even by monochromatic light. Color is perceived by the differences in stimulation between cone types. RGB is a model which allows us to reproduce color, and it is useful because it can be mapped to LMS using a linear transformation. However, RGB is not how we perceive light.