It's not that magenta doesn't exist in nature (there are tons of magenta flowers, for instance), but that magenta doesn't exist on the visible spectrum of light (along with brown and grey). This comes with the understanding that the colors we perceive aren't just wavelengths, but mixtures of colors in relation to other colors within our view.

how many of these ideas come from Br*tain where everything is just naturally desaturated

so true

i'm the only one that perceives the true color of the "create post" button on hexbear. the rest of you see something bleh/whatever.