I am not sure if current RGB tech, in general, would allow the user an infinite or good enough control/adjustment to achieve a perfect match. Even if so, perhaps the key phrase ''...if done correctly'' indicates many users just do a sloppy job, either due to lack of skill or patience. Anyway, have you come across a job done correctly (and link please)?
Anyway, I would embrace RGB if it serves a function other than just giving aesthetic. For example, it would be nice if the colour changes to reflect a change of a component's frequency, speed or temperatures. (I think Asus (?) does have a function to link it with temperature but somehow it was so buggy that I gave up long time ago)