Interesting picture it paints, but perhaps short sighted.
Part of the rise of the PC IMHO: owes to the level of binary compatibility Intel’s x86 processors maintained, and the relatively open hardware architecture around that processor. I don’t think I even met a 5 1/4” our Tandy failed to run until the late ‘90s. Which surprises me even more today than it did then.
I rather like ARM’s approach to the whole IP core thing. ARM processors are largely ARM processors the way Intel processors are largely Intel processors. But the relationship between architecture and a product in your hands is quite different. Because of this we have a very broad range of ARM based products and vendors out there, and while compiling code retains strong compatibility the overall hardware varies significantly.
While ARM largely focused on doing its share well, and other companies doing what they do well. Intel largely retained control over its niche, occasionally spreading into other hardware fronts. In practice Intel and AMD are the only big players in x86 today, and Intel has often helmed the development. You can get an ARM based processor from more vendors than you can shake a stick at, or given sufficient cash and effort start developing your own hardware around it. If you want an x86 then odds are you’re buying Intel, or second sourcing from AMD.
While I think the compatibility made a big difference, I’m not so sure that we benefited from Intel’s monopoly over its ISA. When I think about why there are few cheap ass x86 SBCs, I usually think of this as “Because that’s not Intel’s market” — and Intel’s the real stick in that mud.