If we're basing this on 'good music' as opposed to talent, then your prior response to my list of artists is completely subjective. Good music is judged by a person's opinion. It's based on your taste, not the music they actually make. If we're basing it on fans, your 'average' remark holds no water. If we're basing it on skill, still no dice. Or sales. Or critical acclaim. These are all things that artists produced by Rick Rubin has. So your argument based on your subjective tastes can, in principle, be applied to any producer as long as the person saying so has tastes that go against what is in that producer's history.