I had the same question, as my first reaction was "this looks like such a hack, I am sure there are better tools for this," so I poked into the user manual[0] and found this quote:
> Driven by the frustration of creating charts within design applications and inspired by typefaces such as Beowolf and PicLig, Travis Kochel saw an opportunity to take advantage of OpenType technology to simplify the process.
Reading between the lines, "design applications" is very likely referring mostly to Adobe InDesign and Illustrator. I can see it being useful for the (somewhat niche?) use case that the creator had, which is quickly creating simple charts within Adobe products.