AFAIK Intel GPUs are the most common. Usually embedded chips are less capable than installable cards, and hence even if they have reliable drivers, they will not be able to support higher versions that demand features which are not available in those embedded hardware.
As I mentioned before, GL is an implementation which require considerable effort and dedication to come up with a reliable and stable implementation vs. Direct3D approach of separating drivers from implementation.
I wish we could promote OpenGL to this approach and have the ARB/Khronos become responsible for the core implementation, and let IHVs make drivers and extensions.
I bet this is the solution rather than pushing IHVs to create reliable “drivers,” and bug them all the time by not well supporting GL.
I think Mac OS adopted this approach and therefore it has the GL as the reliable standard for it’s 2D/3D graphics.