The Ostrich always thinks that if her head is covered in the sand, no one can see any of her! Same philosophy applies to those telling parents to check up on what their kids are looking at on chat rooms and such and cut them off. Kids aren't likely to be too interested in such things if the atmosphere in which they are raised doesn't go to or watch pornographic movies, cheat on their taxes, cheat stores out of goods and services, curse and lambast each other like drunken sailors, and on and on.
It is very similar to controlling quality in a manufactured product: if you try to inspect the quality in at the end of the line, rather than properly design and train well beforehand, then you will fail. Our desired quick fixes doesn't work in these cases. Talking and yacking and meeting does nothing with a teenager.