Just so I understand, since the iPhone was the first phone Apple made, are you saying you stopped using their PCs (and music players?) because they'd made a phone? If you were happy with their other products up to that point, how does the phone change the grand scheme of things? I'd want to hear what your ideology is.
I thought Macs would become less open and less important for Apple in the future, with their marked shift to mobile.
I think it was the right decision. Almost a decade later, Macs still lack components I think are key for a developer. For example, they don't ship with a package manager.
I understand Apple's focus on mobile, since that's what brings most earnings, but as a developer freedom is very important to me. Not just from an ideological point of view. Also for convenience reasons. E.g., I cannot imagine going back to floating window managers. Getting a tiling one running on Mac is a bit of a hack. I prefer Arch, Nix and friends.
Strictly speaking they are. Of course, it doesn't help that they put most of the system in one package :) (com.apple.pkg.Essentials).
At any rate, Homebrew and MacPorts are only five minutes away. Even after 22 years of experience with various Linux distributions, I still prefer Homebrew as my package manager. (Mostly because adding your own custom formulae is so easy and new packages are in more quickly than in e.g. Debian.)