Some of the problems with the “clear elementary school mathematics” (possibly already mentioned:
1. Most basic problem (a poster already mentioned this one): Just because boys start dating at 23ish and girls start dating at 19, that doesn’t mean that girls get married at 19 and boys get married at 23.
In fact, my impression (based on a handful of people, and no more conclusive than the opposing theory) is that there are many girls who end up in shidduchim for years precisely because they start dating at 19 but don’t end up getting married until they are a few years older, precisely because most girls and boys do end up marrying people who are close to their age!
Not only that, but since the reason for the concern is the fact that girls are stressed out about being in shidduchim for a few years, it would actually make a lot of sense for them to NOT start shidduchim right away.
For at least 2 good reasons
: 1. They probably won’t have to date for as long since they won’t be waiting for their zivug to grow up and start dating
2. If they focus on something else (work or school) meanwhile, they will have another focus in life and won’t be so stressed about not finding their beshert right away. And for those who are anti-college (like myself), it doesn’t have to be college – how about setting up some Shana Bet/Gimmel, etc programs for girls, so they can actually learn some of the things they are obligated to know? And/or they can take a practical course or get started at teaching, work, etc?
3. If in fact there is an age-gap issue, it will solve that problem without the boys getting married before they are ready and causing the divorce crisis to grow.