Earlier quoted context omitted.
What could you buy before, apart from the Mac? Perhaps we need a definition of GPC?
You have to go back a long time, but just the Apple II[1] technically, and maybe the Newton, but both would be less general than a pre-App Store 2007 iPhone because Safari is such a difference maker. [1]: I, III, Lisa, too, but I mean you get the gist,
It has a real UNIX terminal. I can write code in nearly any programming language. There are thousands of packages that I can install easily with Homebrew. It feels general purpose to me.