There's a simpler explanation than appealing to math the author admits not understanding: male attractiveness ages better. A 40 year old man can be attractive to 20 year old women, but a 40 year old woman is rarely attractive to 20 year old men. In other words, women past their prime who restrict themselves to mates their own age will may be in relatively low demand.
The opposite is true. Because women in their narrow age range of attractiveness get paired with men in a much broader age range of attractiveness, that would create a shortage of women. Say, if women 25-35 date men 30-45, there are 50% more men in that group. or combining folk wisdom and math: d(half your age + 7) / d (age) However, the fact that men propose and women decide creates an inversion. Early marriages take…
Furthermore, the theory that men are trying hard to marry, and the most attractive ones "succeed" to marry at a younger age, just does not seem to be realistic, especially not in modern society. There are good reasons for men not to marry early.