Well, if you're asking me, I'd say Intel is successful despite the technical shortcomings of the x86 ISA, not due to any technical advantages of it. Intel has the benefit of huge volumes (thanks to x86, yes), and they are very very good at chucking out big silicon wafers economically with low defect rates.

Thanks to those advantages, Intel can overcome the disadvantages of the ISA. Which aren't that big in their main markets, that is relatively high end cores.