It's a well known fact that it is quite difficult for some parents to setup and use parental controls, I believe it was just to fully explain it to people that might not know much about how parental controls work.
It used to be a developer presentation. Now the main WWDC keynote is just another product-focused Apple event (since it might as well be one if the tech press is already flying out for it), and the more in-the-weeds developer talks are held on other days.
Even then it could have been 15% of the time with literally the same info.