Downward facing dog pose is difficult for beginners. Hamstrings are tight, the low back isn’t aligned well and the backs of the legs are tense enough to prevent much movement of the heels towards the floor. This version takes the lower body out of the equation.
Working on the arms, upper back and cervical spine alone allows for more precise alignment and exploration without worry. The weight is lessened due to our positioning in gravity and nuances are noticed while being in the pose longer than you can hold the traditional pose. Try it out.