Well, and if you're not trying to imply that we are at peak cognitive ability at the age of 13 (and I at least hope you don't believe that) this should be hint number one for you that the way you think maturity works is probably wrong.
It also shows me that you didn't even read the short excerpts I provided for you. Here, again:
(...) For the current discussion, the key point is that there is no single progression that encompasses functional maturation. Neural activity intensifies and reduces, varies quantitatively and qualitatively, in linear and nonlinear ways that are both linked to—and independent of—behavioral differences across development. Each of these patterns reflects developmental progress, but the wide range of ‘‘journeys’’ prohibits a simple definition of what emerging brain functional maturity looks like. (...)
Or another quote from that paper:
(...) Measures of widespread brain connectivity shift in complex ways from childhood to adulthood, characterized by reductions in local connections and rises in distributed connections. These connectivity-based shifts are thought to reflect a brain that is becoming more efficient in its in-network communication and more integrated in its cross-network communication (...)
Since you seem confident in your grasp of the topic I guess those two should answer your question.
You chose to ignore all of the obvious signs of adulthood. Instead you want to cherry-pick a few insignificant changes in the brain and say "these are the only things that matter for maturity"
Sorry. That's just very stupid.
It would be equally valid to claim that pubic hair, or menstruation, or any other adult trait is the only one that matters.
You think that there's a difference between 26 year olds and 16 year olds. Well, yes, there is. But many 26 year olds can pass for 16 and vice versa. Because they are both adults. 16 year olds cannot pass for 6 year olds or vice versa. 6 year olds are children.
After puberty humans are adults. This is not difficult. Desperately searching for neuological data so you can claim 17 year olds are children is dumb. Stop doing it. Nobody benefits from you supporting bigotry. Stop it.
It would be equally valid to claim that pubic hair, or menstruation, or any other adult trait is the only one that matters.
This is exactly what you're proposing by claiming that the Tanner Scale is the only determinant. Like really, exactly this. It's beautiful how you're debunking yourself.
Your position, that puberty is irrelevant, and the only thing that makes humans adults is a vague kind of "maturity" measured only by minute changes in the least-understood organ in the human body, is appallingly stupid.
Like, I can't believe that you're not just trolling me. How on earth can you claim something so obviously not true?
I'm blocking you. Rethink your life. You don't have to be a useless blockhead troll forever.