The ONLY way children have access to the internet* is if an adult buys a device and hands it to them. The vast majority of kids under 14 is not gonna scrape up enough money for a mobile device that they can use to connect to a free hotspot and be online 24/7. Any internet related bad behaviour is 100% the fault of negligent parents who give their children unfiltered access to the murder, rape. racism and bigotry firehose that is the modern internet.
That's it.
My friends with kids all monitor and control internet access very closely. And before you say "BuT tHaTs A lOt Of WoRk" them maybe you should not have kids. It is a decision to make and raise a new conscious mind, if that seems too hard then don't fuckin do it.
*access at school is monitored and hardly equivalent to the hours a day spent scrolling at home.