Children will learn social skills.
Kids MAY learn social skills if internet is prohibited. Kids may also learn bad social skills by playing with others outside with bad social skills. If given access to the internet children MAY be exposed to a variety of social skills they would otherwise not encounter from many cultures around the world.
Kids will end up settling with what they have, which may be bad. The internet allows kids to socialize with people like them, rather than someone who will be a bad influence.