CCA lost its appeal I think in the 80s, when comics grew more darker and serious. If the initial concern was all "juicy" material, then it became a cosmetic decor, nothing else. Which is paradoxal, because one issue of Elvira House of Mystery (don't know which one) had no CCA seal and allegedly sold poorly. But since then, it became practically useless. In its beginnings, the seal was quite restrictive, at its end, a joke and some comics I read, for example, in 2000s, that had CCA, would never receive CCA in the Silver or Bronze age (i think there was a bare bum in Batman RIP). Then again, Death in the Family had started with Dynamic duo beating child pornographers, and it was in the late 80s.
I don't know if CCA had anything to do with it, but famously Frank Miller, Howard Chaykin and Alan Moore had fallout with DC (in Alan's case, plus Watchmen controversy) who left the company over censorship issues. Howard returned though in the 1990, with Twilight, that carried "suggested for mature audiences".