Imagine how big Apple would/could be if they embraced open hardware. They do have a moat here. macOS is so bloated, I hate it, but the hardware is just so much better than anything else.
The Intel period of MacBooks allowed a more direct comparison. Don't think macOS itself is the differentiator vs Windows. But vs Linux, well even Linux on a non-Apple laptop tends to mean screwed up power management. The window system might be less efficient too.
Is Apple taking steps to purposefully blocking open stuff, or are they just pointedly ignoring it and continuing to develop new hardware? I am genuinely asking, I don't know myself.
For desktops and laptops, the latter. But for phones and tablets they do not want user control. And even where they do allow it, even a tiny effort in hardware documentation that would make it so much easier never happens. So it's quite hostile overall.
I mean, the "so much better" in my experience is really the battery life.