The belief that young people somehow aren't growing up is a myth and a rationalization of the baby-boomers. It's a way for them to excuse themselves for the social and economic wreck they've created. They've damaged marriage, the family, the economy, the education system, to such an extent that they need someone to blame for the miserable future they've created - so of course they're going to blame their own children for not being able to easily find a good-paying job and a reasonably affordable place to live by their early 20s.
All this crap about children "not growing up" is really a matter of economics.
In the old days, and among lower classes, it wasn't uncommon for married children to live with their parents.
Of course when it was economically feasible in the mid 20th century to move into a brand new house and live independently from a young age, things were a lot different. When a college degree was a ticket to a good livelihood, things were a lot different. Things were a lot different 40 years ago. However, as far as "getting what they want" and blaming others for the mess they've made, it's a lot easier to blame young people for being shiftless and "immature" rather than for parents to blame their own deficiencies in judgment.
Human nature hasn't changed. What has changed is we've been raised by a generation raised on television and cultural indoctrination, and they lack imagination. Among traditionalists, they lack an understanding of just how serious being a traditionalist is. That is, you can't have your happy home, and pass it on to the next generation, without sacrifices. That is, you can't raise your children in the slack manner "the greatest generation" did - then expect children to follow the baby boomers worldly path to success, and to remain Catholic. If you want to remain Catholic, you have to follow traditions based on human nature.