It could be part of the solution. This is imperfect of course, and making this foolproof is a fool's errand, so education is necessary as well.

It's imperfect as it's not selective and affect all devices in a home, so adults would often disable it when it gets in the way. If it stays enabled a home, children could counter this by switching DNS, using public WiFi, using a friend's or neighbor's WiFi, ...