I don't have a problem with the child on child headline. I think it was pretty clear in the article that the aggressors were boys, and the point of the headline was to make it clear that these offensives didn't involve adults, it was about the effects of porn on children. And honestly, young girls having inappropriate responses to seeing so much porn happens even if it is much less frequent or aggressive. It's not unheard of at all for girls exposed to inappropriate content or sexual situations to victimise younger or vulnerable kids.
I am not so sure that the parents are so much a factor in terms of teaching kids in a way that would prevent this. I think a lot of the stuff in porn is just so alien to children, in a way much more so that straight violence, and it's so visceral as well. How people conceptualise what consent really means depends a lot on what they think sex looks like, people who have experienced a lot of sex in a questionable context sometimes agree with the idea of consent, but fail when it comes down to actual situations because the way they read the situation is completely bizarre but seems normal to them. It's part of the reason normalising dangerous practices is so dangerous.
Kids just don't have the experience or ability to think through what they see rationally enough to mitigate the potential effect of seeing a lot of rough fake sex onscreen.
I think in the next few years there will be more and more evidence that young people should be avoiding online exposure of any kind, and that will be the way forward with regard to porn as well.