Throughout the course of our lives, we develop a lot of baggage from the various environments that we encounter. We come into this world as pure souls with a clean slate, and as we grow, we adopt various beliefs and idiosyncrasies from our culture, which eventually have an undeniable impact on our personalities as adults.
Whether it is race, class, occupation or belief structure, people identify with cultural labels and use those labels to build their personal model of reality. A child sees the natural world with a clearer perspective because their perception is not clouded with cultural conventions and other prejudices.
It is typical for authoritarian societies to condemn their youth because they have not yet been corrupted and molded into an obedient, mechanized citizen. If the youth of any oppressive nation were able to freely grow without being indoctrinated into the cultural control system, then the whole system would be radically changed within one single generation. The establishment knows that their stranglehold on the human race is unnatural, immoral and insane, which is why their ideals are always met with resistance by the youth culture. The ruling class knows that their only hope to maintain political dominance is to vilify their citizens until they have been indoctrinated into the system, or in other words until they “grow up”.
However, the human mind is resilient and many of us are able to slip into adulthood with minimal psychological corruption. This growing portion of society may not be popular, but they are very often the source of most of the positive progress that has taken place throughout history.
Many creative and rebellious people who are in touch with their inner child typically receive such negative feedback from family and peers that they actually knowingly submit to a culture which makes no sense to them. This is exactly why you have to be a certain age in order to vote or run for political office. The system makes sure to give people enough time to submit to the established cultural model of reality before they are able to have any impact at all on the direction of the society.
There are many cases where we do have much to learn from our elders and it is true that skills which we depend upon for survival have been passed down through the generations. However, when it comes to a government setting cultural norms, there is always an ulterior motive when information is passed down. That motive is always the same, to maintain control of the population and to defend the power of the established institutions, so they endure the next generation. It is very important to learn and mature and it is possible to do so without “growing up” and limiting yourself with cultural prejudices. Being responsible, respectful and peaceful is what makes you a mature adult, it has nothing to do with fitting in to the established culture.