It's an analogy. It's inaccurate as all analogies are. Yet it's useful to make the point that banning children from doing X or Y isn't unprecedented or unacceptable.

Kids go to school for much more than what they learn in class. A fully formed human being that can function in a society requires a lot of social interaction training. That's what school is for in-between classes. If kids are staring down their phones during that time instead of interacting with each other, that training is lost. Worse, instead of that, they get trained on a false social reality as portrayed by whatever enshittified platform they're currently on, based on whatever behavior makes the most money today. Is this enough to visualize the damage phones in hallways cause?