I was going to say, "well, most people aren't actually using a corporate-sponsored distro", but I guess the real question is whether Linux would have become the impressive piece of technology it is today without corporate backing, if there had never been anyone working on it full-time. Maybe FreeBSD would have taken it's place if Linus didn't have enough time to work on it. Either way, it's really hard for me to imagine a non-open system in this position of dominance.
Does it matter? Corporations adopted Linux because of it's openness, and Linux is winning in those areas because of corporations who adopted it because of....
Open doesn't mean 'hobbyist', it merely refers to the freedoms enabled by the code's license...
They adapted it because it was cheaper, not because it was open. Now, open frequently tends to be cheaper, but not always, it isn't an inherent quality of openness.
IBM and Oracle both have in-house operating systems (AIX, z/OS, Solaris), and are both big enough that they have, for all practical purposes, unlimited resources.
Yet both use and push Linux, IBM uses SUSE Enterprise, and Oracle forked Red Hat's OS...
I really doubt either cared about whatever marginal cost they may or may not save. Linux's openness is kind of like natural selection - good features live on, bad ones die.
Open source does make better software (everything else being equal of course).
Ask IBM or Oracle if Linux is losing...