But why fall back on the state to police
every website and service? Not to mention that the Internet is wider than any jurisdiction you can hope to achieve.
Plenty of devices have parental controls and it is your duty as a parent to look into this and understand the consequences when you hand a device to your child that allows them to consume a global diet of media and connects them to a majority of the global populous. It is not unreasonable to expect device/software manufacturers to provide the power to parents to do this and we already have had the free market provide options for this for decades.
To me, it is not any different than to expect a parent to consider the potential consequences of children playing in the streets, etc. and take action. Thus, to me, the people pushing this kind of legislation are either sloppy thinkers or dishonest in what aims they hope to achieve.