And this is my point. So many posts about "you should do this, you should educate them, you should say this.." etc. GAF does not seem to realise that raising a child is not like reading a parenting manual and applying things that should work in theory.
To use your example above. Of course I've spoken to them about this kind of thing. However, a parent's words are never going to trump peer pressure, and if many of their peers have access to this material and actively force expectations, then there's not a lot I can do as a parent. I'd much rather that the potential for their peers to access this material was severely limited.
In addition, I've noticed a lot of "I didn't have a computer / phone until I was 16/18" type posts. Life has changed a lot, and kids mostly have phones when they hit secondary school, and internet usage has become so pervasive, that my kids cannot even check their homework diaries without being online. Everything is done almost exclusively online now, meaning regular access to a computer is pretty much a necessity.