I largely agree with you.

Its interesting to see what I believe to be a generational divide in these comments.

I'm 28. My parents limited my internet and gaming time when I was younger and it mostly just caused resentment and anger at what I believed to be their controlling behaviour. I couldn't wait to move out. When I did move out in University the freedom I spent too much time on the things I wasn't allowed to do before and my grades suffered for it.

I think a lot of comments here have very draconian policies that aren't going to work out the way the parents intended it. I think the harder and more desirable way is to somehow teach them to manage their own time but I have no idea how.