Cuthbert, don't get me wrong, it's a great exercise. It's just that most machines don't "break parallel." So I've seen some people increase their hips strength and flexibility on those machines, but only to the same degree as the depth of the machine. Once they get really low, it still gets harder and harder to spread them. The difference with the bands and sitting below parallel is that you're increasing strength and flexibility in an even lower plane than the machines can. It's a great option for those that don't have access to a machine too. I also think the bands are harder! Plus they rip out leg hair, if you have any, and that builds character.