To the first point: If we assumed this is a dichotomy, which would you prefer? The government banning social media from all minors' devices? Some MDM that disabled it by force during certain hours, requiring intrusive software?
Or, that we remove the problem by removing the tool entirely and without inspecting the devices contents?
You talk about using computers properly, which is a noble goal, but the banning of phones in classrooms has multiple reasons behind it. One of which is the belief that social media and smartphone games are addictive. Should we teach kids how to smoke cigarettes responsibly during their lunch break?
Children can be taught how to use computers in diverse and interesting ways since early age. I know, because I did it with my kid. And I did not exhaust the possibilities, so it can be certainly done much better if educational professionals invest themselves in the topic. As most parents aren't up to the task, schools are supposed to do it since kindergarten, but instead of offering positive and enjoyable examples, they choose to spread the sort of fear-inducing negative technophobic propaganda many people are repeating here.
As for what I mean by technophobic propaganda, just listen to yourself: "the belief that social media and smartphone games are addictive". People aren't stupid. Psychological trickery can get games and media only so far. People crave a variety of experiences. It's not that hard to keep students' attention either by offering an interesting subject, by listening and being honest (for a change), or just by being there as a parent or teacher.
Or, that we remove the problem by removing the tool entirely and without inspecting the devices contents?
You talk about using computers properly, which is a noble goal, but the banning of phones in classrooms has multiple reasons behind it. One of which is the belief that social media and smartphone games are addictive. Should we teach kids how to smoke cigarettes responsibly during their lunch break?