OS/2 was originally developed by a combination of MS and IBM. It was a much better/more stable OS (I developed on it for a couple of years in the early 90s and used to pity those people in our team left on DOS or the toy Windows OS), but it had one major flaw - it was targetted only at IBM hardware, at least in the first few years. With most of the world heading towards cheap clones, that pretty much killed it as a real commercial option.
OS/2 was still a severely compromised design. It was 'better' but it still crashed a lot and would have required a transition to a modern OS.
The IBM requirement was even more onerous because IBM had linked OS/2 with PS/2 Microchannel hardware. IBM had this locked up with patents and could have used it to to control the entire PC industry had it caught on. So everyone else in the 'open' PC world had an interest in seeing OS/2-PS/2 fail.
(IBM was the last major vendor to offer PC-based server hardware because they were trying to protect their midrange machines. I think if OS/2 had taken over, they would have prevented the entire x86 server market from getting off the ground until much later than it did.)
