I always felt like Windows NT and its graphics stack did more to kill off professional users of SGI. 3DS/3DS Max and special codes like SoftImage running on wintel was easy to setup and operate in tv/movie . Each generation of nvidia and intel cpu gave more bang back for the buck for your $200/hr artists and engineers.
Microsoft mooched the shit out of SGI tech, while largely doing as little as possible to help the SGI NT computers succeed.
The big players were on IRIX. Win NT ports of stuff like Maya brought in cheap fast workstations. But, the tooling was crap and a lot of that Win NT share ended up on Linux, not back on IRIX.