That high school is necessarily a place of cliquey behavior and bullying, and that kids may even benefit from it, is not a universal thing. In some countries, viewers of imported American TV shows are baffled by that depiction of high school, because in their high schools there aren’t such hard knocks.
I agree with you, American schools seem particularly bad at breeding these sorts of unhealthy dynamics, and we shouldn't accept it as normal. But even in a better environment, unstructured social interaction with peers still seems like a useful part of growing up/socialization and shouldn't be replaced with kids sucked into their phones.