If rationality is what makes a strong system, then a system based on irrationality is destined to fail. Even if an older generation will not be able to see its failure, the next generation will have to bear the result of its mistake. But basically, things go wrong when people have no freedom of speech.
Without freedom of speech, people cannot discuss their own opinions. When their self-interests are in conflict, there is no way to settle dispute other than obeying the authority. If the authority is not just, the system collapses with unhappy people. No system is perfect, but no system is perfect without freedom of speech.