Because of a discussion in the Virtools forum I revisited the steam hardware statistics page.
It's really nice! I am not sure what audience it does represent – more the hardcore gamer? Looking at the stats there are still low-end/cost systems. Aprox 15% are using the pre dx9 path. Now if we look at the dx8 path stats, then there is aprox. 50% of them using a Geforce FX 5200. It's using the NV34 chip – that's a weak (low-cost) processor but it's still a DX9 card with Shader 2.0 support! Question is now why are they using the DX8 path? If some computer would be badly configured ( no DX9 installed) I guess that card would appear multiple times in the stats, but it does not. Well, only 3.5% are using this card – but still interesting to try to understand the meaning behind those stats.
p.s. Like Godji says on the forum – it's the path choosen by the steam engine. The reason might be thus, that the FX 5200 is simply to weak to run their PS 2.0 path and their fallback is the DX8 rasterizer.