> Working backwards, at some point they are going to be on their own, and if up until that point they are entirely leaning on the fences set up by the parents, and/or don't understand the 'why' behind those fences, they will fail badly.

I've seen situations where the opposite happens. People who aren't exposed to something when they're kids, and then have almost no interest in it when they're on their own as adults. Whereas people who are exposed to it develop an interest and addiction that lasts through adulthood.

I had something similar when I first came across PC, internet and online gaming. Growing up I didn't have any access to these things and I came across them during university, and I kind of got addicted to them and my grades suffered badly. It did help me later in life to adjust my habit around any online gaming. I don't do it at all but sometimes I would install some games, play for few days, and then uninstall them.