A lot of the "multiple generations of families under one roof" type thinking are only practical if you have a large property, which was more common and much cheaper before the industrial revolution, tract housing, high rise apartments, and $2000/mo. rent for 500 square feet. Even if you think it's OK for 3 generations and 20 children to live in a 500 square foot apartment, most others don't want that.
When you have people with more money than they could possibly spend in their entire lives who wouldn't have to work a day in their life if they didn't want to, telling you that people need to start having babies and oh, also they need to work 80 hours a week and "sacrifice" to pay for them as well, lol no thanks.