The "selfish" narrative about child-free people also sheds light on many of our cultural dysfunctions. There's little angst over the many men who choose not to have children, and little social condemnation. Consider simply the difference in meaning of "bachelor" versus "spinster". Women who don't have children are particularly offensive because part of our cultural understanding of the ideal female hinges on being nurturing, emotional and care-giving. To reject childbearing pushes back on the basic assumption that women have an obligation always to make their lives about someone else.
I don’t see anything in this article or the studies it discusses that refutes the idea that weight training stunts growth. You go into much detail about how it adds strength, but you never cite any study that shows it doesn’t stunt growth. I think it is entirely possible that those child laborers in Japan were quite strong, even if their growth was stunted. So why are you pushing weight training for children as young as 6 as “essential,” when you don’t even have any long-term safety studies to show that it doesn’t stunt their growth?