Yes they are, but human beings live in a society and we look out for each other. Sayings such as "it takes a village to raise a child" isn't just a pithy quote. Any parent will tell you from their lived experience that it is true.

Most parents do a reasonably good job of regulating the physical environment their child exists in. At the same time, a lot of parents are out of their depth keeping up with all the threats that exist on the Internet.

Like with security of systems, there has to be defense in depth against these threats to children. Regulation is one of them. Parental efforts are another.