1. The author doesn't understand bookkeeping. 2. The author doesn't somehow believes that emulated teletypes are a good substrate for building user interfaces. 3. The author has spent significant time writing a bookkeeping tool for his business instead of doing something that will move the business forward.
If you're thinking about writing an open source accounting program, spend time mastering GnuCash first. If you feel like you can't do what you need with that and cannot possibly extend it in the way that you need, then write your own.