1) TIME LIMITATION: I need to finish the child-having process by age 36 or so. I want to have a large family, so to have 5 kids, I should start at 28, one kid/2 years. Tracing back, that means I should get married at 27 and find "the one" at ~26. The upper limit of ages to have kids is greater for men, by a decade.
2) ASYMMETRY IN NUMBER OF POTENTIAL PARTNERS: Say, I decide to have a smaller family with 2-3 kids - that would mean I could get married at 33-34 and still be in my productive zone. Well who am I going to potentially marry when I am 33: guys who are 32+ who are not married. Who will unmarried guys 32+ marry: women ages 24 and above. It's not a self-imposed limitation - I might be fine dating 24 year old guys, but would a 24 year old guy date a 33 year old woman, with the intention to get married if all goes well? I doubt it.
So small family or large family, I need to get married by age 27, where I have the maximum number of options to find my soul mate from. Men can get married at 37 and still have many options in choosing their partners.
And the extra decade without family responsibilities without limiting your options for spouses, I would argue, is the biggest differentiator in the workplace successes.