re: "human psychological development doesn’t end until about 23-25"
This is an urban myth. It has been thoroughly debunked.
re: "our level of intelligence requires a longer incubation time"
Your example was dogs. They reach adulthood in around 1 year. We take longer, yes, about 14 years.
What is "general maturity"? What is the scientific tool used to measure it?
or you just made up some bullshit to justify your bigotry against young adults aged 14-20?