So it’s not that there aren’t still people who could conceivably switch to Macs, it’s that Apple decided they didn’t need more converts quite as badly anymore.
Still, only my theory of course.
At this state in the company's life there is a disconnect between those who make the software and those who make the business decisions.
I don't think it's likely that Apple's board just decided to give up attracting new customers, and any apparent decline in quality is likely attributed to bad management; ineptitude, rather than purpose.
Occam's Razor supports this hypothesis.
The DEC Employee Handbook made a big deal out of Doing the Right Thing. Obviously that was subjective, frequently debatable, and sometimes just a pain in the ass - but it was a guiding principle for engineers of that generation, and for engineers who became managers.
And it produced some outstanding engineering and innovation.
Because it actually means "Do the best work you can, for your own self-respect, and also because you respect your users."
That's light years away from "Screw as much money out of your customers as you can, as many overtime hours out of your developers as you can, and if the product is broken - who cares if the money keeps coming in?"