I don’t necessarily disagree but there have been attempts to make laws censoring access to online porn for under 18s since the mid to late 90s. It is probably easier to access and more prevalent now so those laws haven’t been successful. (The EFA has a lot of historical info on the various censorship attempts here in Australia https://efa.org.au/censorship/)

The harm from social media access isn’t as clear cut either. I think social media, if used carefully, can provide benefits for some children for example if they are living in isolated areas, and there is some good educational content too. I personally feel it should be left to the parents to make decisions on what is best for their kids.