Decisions like that trickle up from what developers and IT guys want. There was a generation that was raised on Solaris, and those folks built the first generation web on Solaris-on-SPARC with Oracle databases. But, then the next generation came along, and they hadn't learned UNIX in college on Solaris boxes. They'd learned on Linux in their parent's basement.

I came up during that middle era when the shift was happening. I was an early adopter of Linux, but all of the real training I got (my employer at the time paid for it) was Solaris-based. But, even with the training and access to Solaris, I prefered Linux. I just had more comfort with it because it was my daily driver. When people I worked for were making decisions about OS, the recommendation they nearly always got from me was "Linux". And, I believe that played out millions of times to get us to the world we're in today.

So, yeah, Solaris was competing with free, but not always at the business level...the part that mattered was "how many people with influence are using this OS as their daily driver?" And, Linux was/is a phenomenon. People love Linux. People loved Solaris, too, but it was a much lower number due to lack of access...early days of Linux, you couldn't even get Solaris without a SPARC box to run it on. Later, they made x86 Solaris free, but it was too little too late, and by that time Linux was better than Solaris on a number of extremely important metrics (package management and package selection, for example, but also in terms of just plain fun).