"Someone I know" is Puppy Games (http://www.puppygames.net) and they get a 65% success rate for OpenGL on Windows. 35% *is* a massive failure rate. Totally unacceptable.
I'm not sure that's the case any more. For a while, Nvidia had their OpenGL drivers as a separate download which confused a lot of users. I remember that PrinceC mentioned in the Alien Flux postmortem that that was the biggest cause of failure. They stopped doing that over a year ago and everything's bundled in to one package now.