I don't know why you seem to be so adamant about defending phone use in class. Maybe we're getting hung up on the details here. "Ban" doesn't necessarily mean turning schools into a phone-free zone, it could (and probably should) just mean keeping phones out of sight and out of mind during instructional time.
Bullying is, was, and will continue to be a thing, and it's beside the point here, because phones are not some magic solution you think they are.