amom > Years ago I think it was more common, but today
I think this is because a couple of generation ago, there were working families that spent their meager earnings to send their kids to yeshiva and then even kollel out of love of Torah and out of fear of devastation that was happening with the Jewish community in America. Currently, you often have (statistically, I am not trying to stereotype) parents who do not have serious earnings with, Baruch Hashem, large families, and they are not able to support everyone. Others, and this sounds like your MiL, discovered that there is now a strong community that can support ehriche yidden who earn a living and stay true to Torah, and so they see that their children can combine both. This is a difference of opinions and everyone can easily bring proofs for their side and the answer may be different for different people.