Considering the state of the world as a whole, I’d say it’s better to teach kids to question authority even if in this case the law is correct. As for enforcement, even if the majority of kids still access the sites, it’s better that the access is deemed illegal to keep some of the kids away. Plus it’ll keep sites from being able to specifically advertise to kids, which might help as well. It’s not a solution in and of itself, but it’s a good first step.