Quote - Linux gave it the option of being open sourced, which led to rapid improvement.

The open sourcing of Blender was nothing to do with Linux.
When NaN shut down, a buy out of the code was organised so that the code could be open sourced.
See -> http://www.blender.org/blenderorg/blender-foundation/history/

Linux was an easy platform to port to, because is extremely similar to Unix (similarly for MacOS)
I'm not sure, but ISTR that there where ports for Linux and Macs before the Foundation buy out (it was definitely available for Windows in the NaN days).