This position really is about putting your body at the edge of something, that something could be a bed, a chair, or even a pillow. In this variation you can see how A and B have found a pillow that allows them to be aligned (genitally speaking), which makes penetration more comfortable for A and pleasurable for B.
Notice too how B's left hand is under their lower back, which actually tilts their pelvis up even more, changing the angle of penetration.
