Basically 0 people ran linux on the desktop back then and no one was going to run a server for it (there weren't VPS's etc like today).
Discussion
i was running red hat 5.1 in 1998, but not until 2007 did it become my daily driver, and i wasn't on the internet often until 2003
but it was pretty rare anyone who had the patience and skill to do it back then, i think you can say at the time of the inception of bitcoin it was just peeking over the horizon for the majority