The deal with Oklch is that hsl/hsb don’t do a good lightness mapping regarding color perception, but Oklch does. So, if you transform your RGB to lch and move the “l” value, you can easily get a nicer color palette. Also, you can tell the lightness of two colors by looking at the “l” value; that’s not true for hsl/hsb. That’s useful if you want lightness contrast or different hues with a similar lightness.

Other than that, I agree that “chroma” is hard to reason about. But, at least it is easier to reason than the “a”/“b” parameters in “lab”.