In my experience of writing a GL Windows desktop app alone, driver bugs have been the #1 cause of stability problems for real end users. It's a complete nightmare, with pretty much every manufacturer. I guess that's what happens when hardware companies need to write software.
No time for a startup, and we had previously used D3D and had other annoying problems (horrible text rendering, annoying redist issues, etc), so it just had its own set of problems.
