Like much of education policy, this seems to help some at the expense of harming others.

For the intelligent & motivated, there will be unnecessary boredom during downtime/study hall, potential hatred for learning/school, and other negative effects.

For the lackluster students, this policy will help some pay attention to class, learn lessons, and complete work.

In general, however, I'd have to say I'm against it. Any widespread banning of freedoms or ignorance of new technologies will have outsized negative consequences.