Re: Itanic was wildly successful ...
Not to mention that thing called multi-tasking. So what it each app is optimized when the scheduler then dumps you out to run the next thing in queue.
Sun made a similar mistake with sliding stack frames in SPARC; neat idea, until the scheduler comes along and schedules something else.
Itanium was popular with people developing DSP, because it had an FMA instruction. X86 didn't until, what, 5 years ago now? I took the addition of FMA to AVX / SSE as being the signal from Intel that Itanium was finally, irrevocably dead.