In recent years, both young men and women have delayed many transitions. For example, in 2001, half of all 22-year-olds were still in school. Only one in five had a partner (usually common-law), and one in 11 had children.
I've already discussed the problems with using relationships and children as markers of adulthood so we won't get into that again. Today my point is the problem with using the age of 22.
Here in Ontario (which, like it or not, constitutes a statistically influential chunk of the Canadian population), in 1971 and in 2001, if you started kindergarten at the normal age (in September of the calendar year in which you turn 5), then proceed through elementary school, high school (including OAC, which still affected 22-year-olds in 2001), and university at the standard rate of one grade level per year, at the age of 22 you will be in fourth-year university. If you were born in the first half of the calendar year, the entire time you were 22 years old will have been spent in university. If you were born in the second half of the calendar year, you will still be 22 for a few months after graduation.
So still being in school at the age of 22 is not a sign of lack of adulthood. It is simply a sign of being in university. Even if absolutely everyone finished university in four years, graduated, got a job, and married in quick succession, and then promptly got themselves knocked up, half of 22-year-olds would still be in school, and the vast majority would not be married yet (because some people are going to want to have a wedding that involves some planning) or have children yet.
If they want to make these kinds of value judgements, they should really pick a slightly older age.