Comment by refulgentis

Because it is a matmul best-effort approximation of a perceptual color space, not a perceptual one, and in my experience that's a significant difference when deployed and for design. YMMV. :)

I cringe myself, it sounds like a nitpick, but it's an extremely significant upgrade in every case.

Most concretely, if I use actual L*, design can use palettes linked to L* and vary hue / colorfulness while meeting any contrast standard.