I suppose you've got a point; if the middle class of Americans constantly have their careers destroyed, eventually we'll return to a third world sort of existence where childcare is provided by extended relatives.

However, most people in America can't rely on grandparents for childcare. One reason is we have children much older than people in the third world do - if two generations have children at age 38, it's not very reasonable to be expecting a 76 year old to provide child care.