Such language implies that the brain eventually reaches a kind of ideal state when it is “done.” But there is no final, optimal state.
The human brain is not a soufflé that gradually expands over time and finally finishes baking at age 30.
Yes, we can identify and label periods of dramatic development—or windows of heightened plasticity—but that should not eclipse the fact that brain changes throughout life.
Whether we can, at this moment in time, meaningfully link this life stage to neuroscience seems a tenuous proposition at best.
By itself, brain biology does not dictate who we are.
The members of any one age group are not reducible to a few distinguishing structural changes in the brain.
Ultimately, the fact that a twenty-something has weaker bridges between various brain regions than someone in their thirties is not hugely important—it’s just one aspect of a far more complex identity.