I have so many feelings about that New York Times article, most of then negative. Not being tied to a romantic partner, being in graduate school, traveling, and working temporary jobs like TFA doesn’t make you not an adult. Instead of young people delaying adulthood, I think that the meaning of young adulthood is simply changing because of a lot of economic, social and health-related reasons. Marrying and having a child is such an outdated way of measuring the transition to adulthood.
I also disagree that the marker of “real” adulthood is paying all your own bills. There are lots of adults who are financially dependent on others - what about an 85-year-old who lives with her children for health reasons? Or a 34-year-old divorcee who sleeps on a friend’s couch for a few weeks (or months) until she gets on her feet? What about a 40-year-old who still lives in his parents’ basement? Yeah, he’s not independent, but he’s still an adult! What about people who are out of work and struggling? Having financial problems doesn’t take away your adulthood. Working isn’t quite it, either; there are plenty of unemployed adults. When I was in graduate school and my brother was working a full-time job I wouldn’t have said he was more of an adult than me simply because I was still in school.
I think adulthood is more about psychological markers than specific events or financial support. Jeffrey Jensen Arnett has been doing research on modern adulthood for some decades, and his work supports that - he has a great book called Emerging Adulthood. In it, Arnett maintains that there are five distinguishing psychological features that make emerging adulthood (roughly 18 to 25 or 29) different from both adolescence and young adulthood: identity exploration, instability, self-focus, feeling in-between, and possibilities/optimism. The instability one is probably the one most based upon events/life transitions, but even then Arnett focuses more on how emerging adults feel about these commitments - often in their early to mid-twenties people don’t feel ready to commit to one marriage partner, one job, one career, one city or residence. They make constant readjustments to the Plan that they’ve often laid out for themselves.