It's simple math, do you want to get a wife with more or less years of beauty ahead of herself? Twenty-five is just the modern cut-off where it no longer makes sense to invest into marriage, because the pay-out isn't enough. In Muslim countries where women do not get a say, girls get married off at like 6 years old in some cases to maximize the pay-off.

Western countries also used to be similar to that. One of the most famous love stories in our culture is Romeo and Juliet, where they run off and get married without their parents consent by a random priest. Juliet is aged 14 at that point, while Romeo is a young man.

So pretending that twenty isn't old enough to marry, when in fact 20+ is already really, really late for girls isn't doing anyone a favor. It's bad investment advice. Women interested in marriage need to be aware that there's a time limit and setting it at 25 is already very generous.