Because it takes the place of shortening in keeping the chocolate more free - flowing and making it more smooth, which is exactly what we're looking for in this dip (here's a great little article about that, as well as other chocolate - related topics). (twohealthykitchens.com)
If you fancy learning a bit more about the rich history of this rich bread, here is a great little article about it. (thesashadiaries.com)
Here is a great little article that best describes my two faves: (nicolejardim.com)