Everything is a tradeoff. They get parts for cheap from certain manufacturers. Those have proprietary firmware that you and I can't have the source code to. Everything else is open source. For me, that's fine. It lets me buy them for much cheaper. You could probably design your own board and find completely open source hardware and software yourself, but I doubt if there's much profit in it. If you have a better path and can keep the board as cheap as it is then you should probably get in touch with their engineers.