The privacy and security issues of this are pretty obvious. However I do think that the easy accessibility and ubiquity of porn and highly sexualized content for children and tweens is a serious problem that people who make fun of porn restriction efforts fail to address or even acknowledge.
Certainly a lot of the responsibility falls on guardians, but it's hard to moderate when you're up against the giant machines of social media. They need help to limit exposure. And this isn't some prudish "oh no protect the children from the titty and the peen" attitude. I don't think most people feel comfortable with the idea of 10-year olds sharing videos of aggressive gang banging or throat fucking like it's a normal thing. And obviously this isn't exclusive to porn. Plenty of explicit and gruesomely violent content out there to be worried about. But the internet footprint of porn dwarfs everything else put together.