Being able to reach both hands behind your back and touch or clasp your fingertips is a challenging goal lots of people like to work towards. This type of flexibility can be helpful for yogis who like to work on funky arm binds (it’s the same position used in Gomukhasana or Cow Face Pose, but the flexibility can translate to other arm binds as well), for aerialists and pole dancers who need funk shoulder rotation and behind-the-back reaches to grab their apparatus, and for regular Average Joe folks who want enough shoulder mobility to scratch an itch on their back. Personally, I find having a big range of motion in this pose helpful because it allows my to put sunscreen on my own back without needing anyone else’s help (maybe not a primary motivation for most people, but certainly a plus in my book!).