The view is that a prepubescent minor engaging in explicit sexual activities normalizes them with a younger age demographic, vis-a-vis increasing the viewpoint that adolescents of that age are of sexual maturity (to an extent) and that will attract adults who fetishize those minors.

Pedophilia is not simply an “adult fucking a kid,” but an adult engaging in activities of a sexual nature with children. So buying and using a sex toy with a twelve year old would fall under the child predator umbrella.