A youth pastor at our church did lots of research on this and even wrote a book on it.
He said it is delaying kid’s growth and “finding out who they are”. Back in Mary and Joseph’s day they knew “who they were” at a very young age because they had only their family/village/tribal values that guided them. For the women - their first period and they were a woman.
As the years have gone by, the idea of a “tribe” has faded. Easier travel between villages, then the printed word, radio, TV, computers, and now 24/7 internet. It makes it a lot more difficult to figure out who you are when instead of the 20 or so ideals set forth by your family/tribe are now 20,000 conflicting ideas.
When he spoke at church he said he had written the book 4 years ago or something. And the research (not his - but a variety of others) said the average age of an “adult” male ranged from 24 to 27 or something like that. He had just done a rewrite and wanted to put in new statistics, etc.
He said that he was amazed to find that more recent research put “adult” males at 28 to 32 now! He said something like “You can believe it or not - but that is what the various researchers indicate. And believe me - I know plenty of 28-year olds that you wouldn’t consider to be adults!”
Later I mentioned a neighbor guy to my wife and she just gave a disgusted look. Wife, three kids - he was probably 34 at the time. Acts like I did when I was 17.