I’m still waiting for proof that there are more single girls then boys. And the number of baalei teshuva, overseas shidduchim, girls who marry into a different community minus the number of girls who are born into the yeshivish community who don’t reach shidduch age in the yeshivish community would certainly make for some interesting information. But we don’t have that, do we?
That’s not what they’re suggesting
First you tell me there are more single girls and to fix that, boys should start dating earlier and marry closer in age or girls older than themselves. Now you tell me they’re not encouraging it on a large scale (with approval from a rebbe). How does encouraging a small amount of people to follow those rules help match the numbers you keep talking about?
if you don’t understand the math
You keep talking about birthrate, which is nice, but it would be ridiculous to use that to assess the situation in its entirety.
The solutions of NASI as I see it: have people marry younger and pay shadchanim more (and I’m not sure how doing that will miraculously produce more shidduch aged boys).