Sure, because depression and trauma clearly must be due to the smartphone. It’s not like the smartphone might be the escape route and you’re now locking the child in to whatever caused the trauma (most likely either school, domestic violence or loss / isolation).

Not saying it can’t possibly be cyber-bullying or the s̶o̶c̶i̶a̶l̶ ̶a̶l̶g̶o̶r̶i̶t̶h̶m̶ manipulation engine, but just blindly taking away the things your child is escaping into the most is a shortcut to either an estranged or dead one.