If you do it correctly, it will definitely traction the back, but also the lats and the arms, of course. The trick is to put enough weight on the pelvis with your hands.
This is not a pure back traction technique like some others. It combines the back and the arms. You will feel it more in the arms because they are much thinner than the back. It is actually not so easy to feel traction in the spine since the back is such a large part of your anatomy with lots of muscles. That's why if you traction arms and back together, it feels like it is mostly happening in your arms or lats, in this case.