On top of that they're doing the #1 thing you're not supposed to do in development: completely rewriting a working system.
Common misconception. You shouldn't completely rewrite a working system if there isn't a need. But what if there's something that working system doesn't provide you need to succeed, or an associated cost that's a deal killer? The FOSS world (and the proprietary world) are both filled with successful examples of people rewriting working systems. Starting from scratch isn't always a bad move.