The squat is a foundational movement that everyone should be able to do, but many people have trouble doing properly today. Lack of hip mobility and stability as well as core stability are common limitations, as are muscle imbalances. We take a rehabilitative view here, which can be different from a strength or power development one. The fundamental spine and hip position is not negotiable. The foot placement and rotation can be varied in properly functioning people depending on their goals and personal anatomy. A good quality functionally sound squat shows us a lot in terms of overall ability to move properly. I would rather have people do great body weight squats than less than ideal weighted squats.