Another component here is that it might not even be their intellectual property per se; my understanding (from what I've heard from friends who've worked at gra

Another component here is that it might not even be their intellectual property per se; my understanding (from what I've heard from friends who've worked at graphics card companies) is that some of the hardware / OpenGL driver may contain IP that the graphics company has licensed and isn't even allowed to release as F/OSS if they wanted to. IIRC, certain "Intel Integrated Graphics" variants suffered from this problem, and to this day lack good 3D F/OSS drivers.