That's true, but Apple also got behemoths like Adobe and Microsoft to port over their applications to modern APIs (Cocoa and Cocoa Touch).
Which is also a reason why they hardly have a meaningful market share across the enterprise world.
But in the real world when people talk about “mobile software” everyone knows that people are talking about iOS and Android. No one is chasing after the Windows software market, it’s been a diminishing platform for the past decade.
When they actually become a match to laptops and 2-1 convertibles, maybe.
And there Chromebooks are no where to be seen outside US school system, iPad Pros are mostly a gimmick in rich countries and Android 2-1 are basically phone apps with keyboard.
If I ever got back into desktop software, it would be highly specialized low level C/C++ code and not WPF/Sharepoint/UWP software.
I'm using AHGotoPage() because NSHelpManager has no equivalent and nobody has been able to explain to me how to make that class do a similar task reliably. (In hindsight, AppleHelp is such a disaster that I should have just avoided it entirely, as almost every other app does.) MAS reviewers have given me grief over many things my app does, but never any Carbon calls.
The last time I saw any Carbon APIs deprecated was 10.8, I think (6 years ago).