Apple doesn't really appeat to care about backward compatibility though. They break lots of things with every release of the OS. I would give that excuse to Microsoft, but not Apple.

True. But the legacy code is still there.

Which is the worst of both worlds.

Disagree. Microsoft keep making new APIs and depricating old ones. With Mac you got cocoa which goes back to 1989 and you can still use.

It might not be backwards compatible but from a developers perspective it is nice to be able to reuse old knowledge.

I think Apple has been much better than MS or Linux in continously modernizing and upgrading what they have. On windows and linux things tend to become dead ends as new flashy APIs appear.

Sure old win32 and motif apps might still run but nobody really develops using these APIs anymore.

On windows I first use win32, then MFC, then it was WinForms. Then all of that got depricated and we got WPF, silverlight and then I sort of lost track of what was going on. Meanwhile on Linux people used tcl/tk for GUIs early on. And there was motif, wxeindows. KDE and Gnome went through several full rewrites.

If we look at MacOS X as the modern version of NeXTSTEP the core technology has been remarkable stable.

Sure they have broken compatibility plenty of times but the principles and API are at their core the same.

Quickdraw VR, Quickdraw 3D, NetTalk, JavaBridge, Carbon, Objective-C GC, RubyCocoa, WebObjects, ....

One just needs to look into the right spot.

Doesn't work, isn't maintained, but remains as an attack vector and failure mode.