Dude you realize that is exactly what is going on now, right? Just because most women wed around 26 doesn’t mean there weren’t still significant numbers of teens being courted. These may not have been the NORM, but they were common enough.
Just like now, over all teens marrying is pretty rare in the US, but you still have like 200K in 15 years. Enough that Corey says, “The grooming of children to marry adult men is a common practice in American evangelical circles…”
Though words like “common” and “rare” can be subjective with out well defined meanings.