The characterization of Microsoft being disorganized because they were working on OpenGL at the same time as Direct3D is a direct result of misunderstanding this difference. Microsoft had to address to entirely different markets: gamers for whom high frame rates were much more important than fidelity and engineers for whom accurate rendering was important (Even today, high end graphics cards for Windows workstations run OpenGL.)
[http://www.nvidia.com/object/autocad_pd_perf_drivers.html] [http://en.wikipedia.org/wiki/Quake_engine#Reducing_3D_comple...]
3dLabs involvement with the development of improvements to OpenGL is symptomatic of OpenGL's emphasis on fidelity in rendering and the legacy of SGI from whence it evolved. The slow pace was perfectly acceptable to a group of serious people who care about standards and don't care about games.
3dLabs is also an example of the distinct segmentation of the consumer and engineering market for graphic cards in the PC market. The second PC I inherited in my first CAD job had was a 386 with an Nth Engine B752 - you could have built a kickass gaming system for the price of the card alone but it wouldn't put much of a dent in the price of an Iris.
[http://www.thecomputerarchive.com/archive/Displays/Video%20C...
Keep in mind that back in the 1990's all sorts of consumer grade graphic card craziness was going on in Windows boxes - e.g. VESA local bus [http://en.wikipedia.org/wiki/VESA_Local_Bus] and the volume of new Windows machines was exploding and many of them were running graphically intensive games.