You brought up several varied points in your post, but some really make me think....
I would so much rather see a boy leaning against a tree reading, than playing with technology..... but what I see more of is a boy or boys huddled up in a tent with a video game, with other cubs that didn't bring their games or tablet computers huddled around watching and wanting a turn. Our CM's sons are the ones with all of the latest gadgets, and it's usually around their tent where you find this huddle. On a campout, I view this tech as a sort of cancer. On a camp out last year, I had my son leave his tech at home. Unfortunately, other boys had theirs. I asked my son to go climb a tree or something, but it's hard when he wants to be right in the huddle!
I wish I could drive a removal of that cancer from our pack, but as mentioned, our CM, as well as other leaders, are the tech crowd and I think view the tech as a way of getting the boys out of their hair so they can burry themselves in their own smartphones.
Your point about TV on the home front is interesting. I was raised without much limit on TV. I have always contented that a kid can learn from TV, even stupid fiction. I feel that I was able to put myself in the situations of the story line and learn from it...... Situations that I may not otherwise find myself in..... shows like Andy Griffith, Brady Bunch, Munsters, Beaver, Lucy, etc.... usually had some sort of moral or social lesson
I think even the newer ones that my kids watch now that aren't nearly as "wholesome", can be educational to a degree.
Still, I do agree with your point that generally speaking kids with stricter limits tend to be more polite and socially well adjusted.
My wife and I limit our kids with TV & tech, but MAYBE not nearly enough.... I'll have to give this some thought for sure.