"Self-restraint" taken as a result of government censorship threats doesn't count. (That's one reason why your form of nanny statism destroys all true morality.)
No, it was self-restraint as a result of popular pressure. The result was great movies that have stood the test of time, not schlock filled with profanity, sex, and violence. And the result of the sewer that is our popular culture is the anecdote I mentioned yesterday: junior high students needing to read on sex-segregated buses to stamp out the epidemic of oral sex on the school bus. This may be your idea of the perfect society, but it sure as hell isn't mine.