Your point on stabilising muscles is on point. This is why pistol squats are worth more than just a body weight * x two-legged squat. This is why yoga is valua

Your point on stabilising muscles is on point. This is why pistol squats are worth more than just a body weight * x two-legged squat. This is why yoga is valuable for more than just flexibility. Isolation of a muscle is all great and can make you look strong, but your body is actually a non-trivial network of muscles distributed across your entire body. Unless your aim is to lift a big number or look big in a specific way, a gymnasts are a better proxy for balanced strength and they rarely do more than BWEs. Personally, I do love a good old fashioned barbell squat though...