Seem to me that Apple and MS focus on different kinds of change.
While Apple may retain the UI across time, they are more than willing to change APIs etc on a whim.
MS on the other hand may change the UI (though outside of 8.x, the core layout and behavior has remained much the same, and even 8.x could to a large degree behave like the older UI) but they bend over backwards to maintain APIs across time.
I get the feel that stable APIs are undervalued as a user retention element.
Being able to get a new computer but install from the same software library (i can hear the _sec people getting hissy already) as was used on the old one makes people more likely to pick the same "platform" over time.
Right, I see that point and would have acknowledged it more explicitly had I time earlier. That's the interesting part of this.
The counter is that Apple caters to a smaller software development community, though several of the tools also see extensive use and support (particularly photoshop). But there's a heck of a lot fundamental functionality on Apple's platforms that you can get without relying on third-party software, or at least, third-party proprietary software. Given the dynamics of proprietary software markets, particularly toward adware, nagware, and malware, this seems a possibly positive development.
(I've made much the same observation in recent years about the Android marketplace, which I see as a growing cesspit, and of the Windows application space, particularly at the peak of its crapware / spyware / adware period in the decade of the 2000s.)
Linux solves the software compatibility problem by allowing for recompiling of software for which the source is freely available, for the most part. This isn't a perfect solution, and there are complex systems which tend to not be particularly forward-compatible. One possible argument is that such complex systems are themselves inherently problematic and ought perhaps be avoided. You may not agree with the argument, but I'd expect you'd admit to its existence.
Microsoft was addressing a different space, and one in which there was a massive focus on desktop-distributed client software, much of it aimed at very specific business applications. This is a major application area for computers, though it's also one that's shifted significantly toward client-server Web-based solutions (or app-based, now). Which presents its own set of features and limitations.
And again, all this is what I was hinting at earlier with noting that you'd presented a very interesting point. I'll be thinking about this for a while.
While Apple may retain the UI across time, they are more than willing to change APIs etc on a whim.
MS on the other hand may change the UI (though outside of 8.x, the core layout and behavior has remained much the same, and even 8.x could to a large degree behave like the older UI) but they bend over backwards to maintain APIs across time.