Currently wondering why we use RGB when the "red" cones in the human eye are most sensitive to yellow light

probably cheaper and perhaps you can't make red as a combination of the others

Red cones are also sensitive to high frequency blue light, so could call it whatever really. How we see purple. But it's about stimulating different cones with different frequencies. Not maximising the response to a given frequency.

@matt-jd I'm guessing that second part is mostly why. While a yellow subpixel would activate the long cones the strongest, it would activate the medium ones along with them, making it impossible to actually display red.