I'm sorry, you're totally wrong. I walk past some basketball courts every day, and there are always games going on. At the middle school, the kids play volleyball, and also spike ball:
Well, I'm glad I didn't read it, because a child should have both unstructured play, fully free of adult supervision AND structured play to learn the ins and outs of working in structured rule-based groups while pursuing something they enjoy.
When I was a kid, I hated structured play to the extent that I would rather not play at all. That even applied to video games; I wanted them to be as open and free as possible, with many ways for me to solve problems (and equally many ways to fail to solve problems). Most games were unplayable to me.
I think this is because I was (and still am) very diligent by nature. I was extremely dutiful and obedient, always did schoolwork to the best of my ability, etc. Playtime was my desperately needed creative outlet, where I could just try things unplanned and discover what I was capable of.
My parents did try to introduce me to some structured activities, but when I didn't click with any of them, they stopped pushing them. Looking back as an adult, I think that was 100% the right call.
Even better, they did not assume my little sister would be like me. They introduced her to structured activities even after I had long left them behind, and she took to them in a way I never did. She was naturally disorganized, basically my opposite, and I think these activities gave her some much-needed balance (in much the same way that unstructured play did for me).
I never played any organized football, but I played a ton of informal touch football, and very occasionally tackle.
Same with most baseball: a bunch of us kids got together and played. In most of the world, it's football ("soccer" as Americans call it).