I feel like your description conflicts.

If adults can't manage themselves with phones then down the road makes no difference.

I feel like experience builds good choices and total bans are like just putting blinders on.

My oldest had supervised access to a phone / tablet for a while, when he downloads a game now he takes the game to gauge how much it relies on micro-transactions and so on and passes on it immediately if he thinks it is bad. That only comes form experience, and probably better to learn it when a parent can talk to him about these things rather than later in life when he is blowing his own money.

> If adults can't manage themselves with phones then down the road makes no difference

Adults today can’t manage. That’s a function of the people and context. Adults tomorrow might. Perhaps because we regulate it. Perhaps because they’re exposed to it more carefully.

> probably better to learn it when a parent can talk to him about these things rather than later in life when he is blowing his own money

None of this requires he have a smartphone at school.