I think it gets at something profound and important: people’s beliefs conform to the group in which they are raised. The filmmaker notes the importance of speaking out if you hold a minority opinion and are surrounded by a majority in error.
The worst thing about public education might be the way it forges a conformity of opinion. Students go through 12 years of brainwashing in political correctness. The ideals of the New Left — egalitarianism, the welfare state, multiculturalism, environmentalism, moral relativism, etc. — are taught not as opinions or one side of the argument, but as the cultural norm to which students are expected to conform.
The antidote to the poison of conformist thinking is independent thinking. The more people are encouraged to look at reality and think and judge for themselves, the better. It’s a good idea to get young people reading The Fountainhead by Ayn Rand, the most powerful portrait of the virtue of independence I have read.