They deserve credit but while IBM did spend lots of money on Linux around 2000, and that helped legitimize Linux. I feel that RH has always been the leader in this industry, and RH Linux was well entrenched in the enterprise long before IBMs big push. So IBM helped but they did not create it, in my view.
I would disagree with RHEL being entrenched by the time of IBMs big push. At the time, you were still more likely to see commercial Unix than Linux at large companies.
Red Hat becoming entrenched wasn't a guarantee in my mind until IBM made that big push. If you could point to a single event that made it likely Linux would take over, without a shadow of a doubt it would be the blessing it received from IBM. There were an enormous number of bigcorps that made initial investment in Linux after that.
