> Do people actually use this?

Yes. OKLCH is actually MORE intuitive when creating shades because it's based around human perception. It also supports wide color spaces like P3, where rgba is, IIRC, bound to sRGB.

The utility of these color spaces and color functions isn't lost just because LLM. Color systems haven't gone anywhere.

Would highly recommend reading up on OKLCH if you haven't already. A lot of people put a lot of effort into promoting this and bringing it to baseline..