> fewer old folks consuming resources and providing little value in return.

As a parent living by my in-laws, I can assure you that, far from providing "little value", raising children without support from grandparents would be severely more difficult. Personally, I see generations trying to be independent of one another as a large factor in making modern childrearing increasing difficult.

And this is aside from the knowledge, and labor that would have been so vital in former times. The old woman spinning and knitting is a historical trope, but when you have to hand make all of your textiles, she becomes quite useful indeed.