POSIWID. The purpose isn't to protect children, it's to control narratives and suppress the preferred targets of TPTB.
Allowlist-based parental controls already exist. Most parents never set them up because it's a pointless battle, their teenagers will just another device that isn't controlled by the parent.
In other words, exactly what their plan is.
Why not just add whitelisted parental controls on childrens phones and be done?