I didn't say fully developed, I said fully capable which in context is to mean that they are capable of going out on the open net without anything they see permanently warping their worldview inaccurately. Its reasonable to shield children from negativity in the world they have no capability of understanding and will end up with warped ideas. At beginning adolescent age that capability is reached, and if they are further shielded from the world they'll form an inaccurate and unhelpful worldview most likely. At best their development will be delayed.