I was one of the hundreds of OS/2 developers at IBM. I can tell you this, at the top of every source module for OS/2, there was this statement "Copyright 1987, Microsoft Corporation."
Yes, MS wrote OS/2 - except for the networking layer and the installation programs - the worst parts of OS/2. When I mentioned that the worst parts of OS/2 were written by IBM, I got may ass chewed out royally!!!
My point? IBM dropped the ball on OS/2. Period. Their management decided that the company's resources would be best spent on developing their software on Wondows.
Don't ask me, ask Gerstner.