The main point of childhood is to develop a solid basic humanity with good habits and a good moral compass. That means moral, intellectual, spiritual, and physical development. Good parenting and a good social environment support these. As such, these goods should be prioritized.
We know that children and teenagers are vulnerable to all sorts of filth that the internet makes available very easily, and indeed even inflicts without consent onto users. Porn, for example, was something that was more difficult to encounter before the internet, and when you did encounter it, it was in smaller amounts. Today, you are a URL away from an unlimited sea of it, and the ubiquity of mobile devices means restricting access is difficult. This makes parenting more challenging. And that's a more pernicious even if common problem. Social media and SFV cause all sorts of developmental harm without suffering the same stigmas as pornography or violence, and so its use continue with the full approval of the social environment.
(And age range here is not so important to discuss; pornography consumption and social media/SFV use is bad for everyone, including adults.)
> Be aware of unintended consequences when you (try to) cut a child off from computer use.
A corollary of what I wrote about is that you have to understand what matters. Becoming a "hacker" isn't the priority of childhood, and it's odd to prioritize that. It isn't worth anything if you are left screwed up by consuming bad content. (Nor does most of the most fruitful experimentation require constant and unfettered internet access. Without maturity and discipline, the internet easily becomes an enabler of shallow and superficial engagement. Deeper exploration is often best facilitated by disconnecting.) It's also senseless to appeal to exceptions.
However, I do think that the most important factor isn't parental controls, but the family environment, what parents teach their children, and the social groups your family and your children move around in. If parents are relying on technology as a substitute for their job as parents, then children will easily fall prey to all sorts of trash. But if children have parents who communicate clearly what they should and should not be doing, maintain a healthy and active family life, and model good behavior by example while penalizing bad behavior, then children will generally stick to good behaviors.
I think law has an important role to play. The former should support the latter. And more fundamentally, this requires a certain backtracking from the anything goes/do what feels good ethos of the contemporary moral landscape. Moral confusion is the biggest factor. Law is effectively a determination of general moral principles within certain socially and culturally concrete circumstances. As the old expression goes, lex iniusta non est lex (an unjust law is not a law). The point of the law is to guard the common good (which is what makes a society) and help steer people away from the bad and toward the good. We all need these to live good lives, and we need to finally put to rest the pernicious notion that the law is not about moral guidance and that all it exists for is to secure our "rights" to whatever we want, where the understanding of rights entails a destructive do what thou wilt relativism. True freedom is not the ability to do whatever you damn well please. It is the ability to do what is good, and to be able to do the good, one must be virtuous - a proper formation - that enables you to be good. Vice cripples our ability to be. A legal system and a society that is supportive of virtue and the good is good for its individual members. One that embraces a bullshit "neutrality" is an easy target for predatory exploitation. There is a great deal of money to be made from vice and stupidity. We become morally defenseless in the face of the wolves. Might becomes right, and in a culture of moral relativism, we internalize this tyrannical false principle.