It isn't just open source. If I was to hack a driver for it, but not release the code and only do some sort of daemon server and documented API replicating anyt

It isn't just open source. If I was to hack a driver for it, but not release the code and only do some sort of daemon server and documented API replicating anything it can already do, it would be the same idea. The problem comes because the reverse engineer hackers don't have a business model to protect. It doesn't matter if that month long project doesn't return any money, because it was damn cool to do. Compare that to Microsoft who requires people to pay them money for the privilege to write code that takes advantage of it. I don't have any numbers, but a large group of small to medium game companies buy SDKs and Development tools for platforms they don't actually produce titles for. This is a significant number of people they don't want "trying" before they buy.