Good day. No, it "only" serves as a joystick, so to speak, to click back and forth between the pictures with right and left (and to manually shift the focus point, for example - then also up/down). However, you can still "zoom out" several times with the zoom buttons on the left side, for example, so that you get a kind of thumbnail overview with which you can also navigate quite quickly. You cannot rotate it (clockwise/counterclockwise) on the D750. What is possible, however, is to "rotate" through the images with the small wheel at the top right when you are zoomed into the image, for example. This allows you to decide very well/quickly between two pictures, for example, which one is sharper.
Was that understandable?