As far as I can tell from the OP's summary, the book could just as well be arguing that having children is a net asset... and instead of wasting resources on your one or two children, you should use them to help a dozen other people have 40 or 80 children.

This is a view I disagree with because the utility function should be evaluated over the entire support range, and maximizing child output on a local time-scale at the cost of a long-term overshoot, collapse, and dark ages (or at worst extinction) does not do that.