This pose shows up a lot in yoga. Like most poses, I was originally introduced to it in the Primary Series of Ashtanga yoga. It looks so simple, like a simple runners stretch. However, the longer you do yoga you realize how complex it is. The deeper you get into the stretch, the more complicated the sensations. It's a super strong hamstring stretch, big hip opener, stretches your back a ton, strengthens your core, and it is also a nice twist for the spine.
Yep, it's an everything pose....like every. other. single. one.