That is a fascinating perspective, which makes sense. I would add that the concept of adultness is also related to seeing a person who is the "adult in the room" regardless of age. In specific, when a situation had a lot of risk and uncertainty, there is a person who can stay calm, likely positive, and always have a plan of what to do to respond.

I read that growing up means finding yourself in circumstances where there are often no other "adults in the room," but you can step up and take the responsibility to manage any uncertainty.