I don't care about RYB and am not talking about RYB because RYB is not an even distribution. It is imbalanced toward the red.
But for example, if we quartered the visible spectrum. That is red to violet. Let's say we did purple (128, 0, 255), chartreuse (128, 255, 0), red (255, 0, 0) and cyan (0, 255, 255). That would be a symetrical arrangement of colors, but it looks really strange.
In fact, even the pallete suited to our eyes, the light primaries, RGB, is a pretty aesthetically displeasing and unnatural looking set of colors. And I know you may say aesthetics are subjective, but there are patterns in human opinion.