Sorry, but you've missed my point. The one-parent-quitting description is to show that the same amount of output/production/work can happen with half the peopl

Sorry, but you've missed my point. The one-parent-quitting description is to show that the same amount of output/production/work can happen with half the people if they are twice as productive. This is to show that increased productivity (more product, same amount of work) is more important than jobs. Increased productivity gives more of everything for everyone. We all know this to be true - if you spend all day napping in the sun, you get nothing achieved. If you spend all day working, you can get many things achieved.