It's the old rivalry between a state-controlled education and parental responsibility. I always say: Let the parents decide what is best for their children! But no interest and supervision at all is the worst of the three choices!
In my view any restriction on the teenager kids is going to boomerang. Rather than a curative measure it is definitely going to sow the seeds of rebellion and a breeding ground for curiosity. The kids have to be guided properly so that they can decide for themselves as to what is good or bad for them. From my side there is a big NO to any restrictions on them, more so with regard to Internet.