> There's also a level of animosity to your parents when they don't trust you that pervades the relationship.
The counter-balance for that is plenty of love, support, and one-on-one time. Building trust, essentially. With that, the kids will understand the reasons for the rules.
> I really question that decision to completely block him out.
I have two children. One child has always successfully-self moderated her screen time and we have never had to step in and correct anything. Zero worries about her.
The other child is the exact opposite. He is not that young anymore but still has no self-moderation. He has his own computer on which he can do an unlimited number of things but if given the choice, he will spend literally ALL of his time on it not even playing video games, but watching YouTube videos of other people playing video games.
Even if we tell him, "here's your computer, you can do ANYTHING except watch YouTube gaming videos," he still ends up watching YouTube gaming videos when he thinks we aren't looking. When he gets caught, we take the computer, tablet, or phone away, and remind him what the rules were. He gets angry and throws an enormous temper tantrum. Rinse and repeat, for years on end. He doesn't seem to be learning any lesson here so the only option we are left with is banning him from Internet-connected devices most of the time.
It's a real bummer to me because free access to computers (as a kid) and the Internet (as a teen) are the only things that turned me into a half-capable human being. I'm worried he won't have that chance due to his inability to self-moderate his screen time, combined with the fact that the Internet is now more of a shopping mall than a library.