i believe that before OSX, the OS itself had no terminal/shell/command prompt, and I suspect Macs were very rarely used for development back then; it was only with Unix-based OSX that it became hugely popular.
Who WAS Apple's customer base during the classic MacOS era? I remember Apple II's dominating when I was in school back in the 1980's. Then in the 1990's when I was in college, all I remember seeing anywhere were PC's. DOS and then Windows for the masses, and this new thing called Slackware Linux for many of us in the CS department. In the 2000's I started hearing about Macs, but only for creative domains like Photosh…
They've also always had a decent base in the creative space-- Photoshop 1.0 being a Mac app had a big impact. Scully's mismanagement of the company meant a lot of people dumped the company in the mid-1990s, though; Jobs' return, the OSX transition, and the Intel switch were all necessary to bring the Mac division back up to where it is today.