Seems like a missed trick, I'm not going to change my accounting system for one app but if it was in the pta ecosystem I could easily see myself using it as a nice front end for my existing data files.
As a GnuCash user, my pipe dream in this area is all of these tools--ledger, beancount, GnuCash, this--operating on the same data format. There are some things I like about each of them but it is not easy to switch back and forth.