Because there's an OGL out there. We can't put "Magic of Incarnum" in the title, but we can certainly tell people in the forums that the mechanics are based on those previously seen in that work.
The races, classes, veils, etc. are all completely new and unique to Dreamscarred Press, and while there is some mechanical overlap in a few of the feats, that's more due to the nature of the system and the fact that there's only so many ways to write "add x for y effect". Dreamscarred Press is very familiar with the OGL and all of its requirements and is operating well inside its parameters on both the Akashic Mysteries and Path of War products.