That is very misleading. No 3D hardware will work properly without drivers from the manufacturer. DirectX requires drivers just the same as OpenGL. Any store-brought machine should already have proper drivers installed. No manufacturer is going to deliberately produce a machine which has sub-par performance.
The fact is Microsoft forced ATI and NVidia to remove hardware OpenGL support from the drivers that ship with XP while spending significant resources ensuring all graphics cards include certified DX support.
Installing drivers from hardware manufacturers also has the following problems:
* many clicks to find the correct driver followed by mega sized download
* DX support in latest drivers often problematic compared to MS certified drivers
* non Doom3 compatible cards unlikely to have glitch free OpenGL support due to lack of benchmarks / industry certification etc.