Among other things, the author of the OP does not adequately address the role of environment in survivability, reproductive success, and genetic expression itself. He mentions birth control. Birth control is a valuable adaptation in certain environments, particularly where sex plays an important social role beyond reproduction (see: Bonobos) or where resources are scarce and would be wasted on excess offspring. But obviously, birth control can be severely maladaptive for an individuals genes and populations that overuse it may be at greater risk of extinction than those that don't.
All your examples are examples which show that birth control is perfectly doable and easy; hence modern birth control - often no births at all, rather than spacing or infanticide - easily passes under the 'that would not be reproductively fit but we want it anyway' criterion.
