I've heard people say, "well kids can get accounts elsewhere and view porn." Look, you have to lead by example. If you're a parent and don't want your kids watching porn, you get a router that does some blocking. It won't get all of it, but you don't allow yourself a bypass either. Explain to you kids, "I know porn is tempting. I think it's wrong and I know it's wrong and try not to watch it." Yes they can still watch it if they want to, but you've let your values be known and they will either share them or dismiss them.
If you don't have any moral issues with porn, well then it really doesn't matter and let you're kids do whatever .. or whatever place in the middle you stand; you explain that to your kids.
But it should be the PARENTS who control that, not big daddy government. Don't outsource your responsibilities as parents.