How very, very true. Only a society with a culture with strong internal moral restraints can be free.
Look at Islam and its unfitness for democracy. Men who demand that women carpet themselves from head to foot with cloth and be isolated from social contact with other men are men who think about rape all the time. Men with no internal restraints, men who apparently cannot control themselves at the sight of female flesh, need despotic restraints to maintain order among them.
That is the fundamental foolishness of libertarianism. Only a society with a strong culture can have weak government. Only a society in which ostracism and disgrace are potent sanctions, only a society where "what the neighbors will say" matters, only a society that in fact would never, ever, regard the use or presence of pornography as acceptable can be libertarian. Government expands when cultural norms no longer hold and laws have to fill the receeding space of honor, morality, and fear of disgrace. The more monocultural a society is, the weaker the government it can have because the coercion of law is replaced by the coercion of ostracism to control negative behavior.
Nobody is saying you should not have the right to ostracize people for engaging in behavior you do not approve of. Nothing in our society requires you to associate with people whose morals you do not like.
You seem to want to take it to the next level, though: you want to use government power to peer into your neighbors' bedrooms to make sure they aren't watching or reading naughty material.
The more monocultural a society is, the weaker the government it can have because the coercion of law is replaced by the coercion of ostracism to control negative behavior.
Despite whatever myths you may have been taught, America has never had only one culture.