I feel like I'm standing between two really stupid positions here.
On the one hand, just let parents teach their kids is basically a state's rights argument. A lot of parents won't teach their kids, so... do we care? Does this matter? We should probably mount a stronger effort then.
On the other hand, we don't need the government to get involved to stop 9 year olds from seeing titties—we just don't! Websites the world over have implemented 2-factor-authentication more or less by themselves (and probably because they want to spy on you). And, no one says the word r----- anymore because if you ever do, a bunch of anti-bullying PSAs will be really annoying about it in your replies.
Not every social problem needs to be solved by swinging around Thor's hammer. We do have other means.