openGL hardware developers

Hi ppl,
This is the closest forum I found to post this topic. I have a couple of questions about hardware that support openGL. I guess that they actually dont implement openGL directly ( I’m sure about SIS chipsets )… this means that the translation job is left to the drivers…
Can anyone tell me the reason why? I was thinkin about implmenting the same in a HDL language. Anyone willing to join in?