>>But in most high-end professional fields, that's not true. Imagine asking a prospective medical resident "did you treat any diseases in high school?" or "how much surgery do you do in your spare time?"

Not a fair comparison because the practice of medicine is not accessible anywhere to the same extent as the practice of programming. You need a license to practice medicine. You don't need one for programming. Similarly, surgeons need facilities and equipment to perform surgeries. The only thing programmers need is a computer.

I think the OP has a point. I know several brilliant mechanical engineers for instance, and every single one of them used to tinker with cars and gadgets and whatever else they could get their hands on when growing up. Indeed, such a background is a strong signal for curiosity, which is an important factor in success and professional growth.