Unfortunately divorce rates in the Frum community are on the rise. I believe this is because many people are not prepared for what marriage is about, and have false expectations. When those expectations aren’t met, they think they made a mistake, and end things. They don’t realize that divorce won’t solve their misconceptions.
I believe very strongly that encouraging 21 year old boys to get married is just going to exasperate the problem. They’re even less likely to be mature enough to know what it takes to have a successful marriage.
I think a better solution for the shidduch crisis is remove the arbitrary and ridiculous stigma against dating a girl older than you. The 24 year old guys should be encouraged to date 24 year old girls, and above. Obviously not a 40 year old woman, but a year or two is no big deal, and a 26 year old with G-d’s help can have many children. So that’s no excuse