That requirement is no different from a GPU, or for any HPC application. Spaghetti code is going to turn out poor performance numbers no matter where you run it; consumer x86 processors and applications are less sensitive in this regard.
With minimal changes I was able to make a Knights Landing Phi system blow 64-core Epyc Milan out of the water performance wise using perfectly normal open-source x86 code, while using less power. For this reason, Xeon Phi was used in plenty of HPC and Top500 machines to great effect.
Itanium’s performance was not convincing due to compiler shortcomings, and its technologies vanished once it failed to gain significant market share. In contrast:
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AVX 512 is still included in Enterprise-grade processors and offers tangible benefits to software that takes advantage of its extensions.
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The Knights Landing core-to-core “mesh” type interconnect formed the basis of Skylake and later Intel processors, supplanting the previous ring-bus interconnect.
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The implementation of the MCDRAM on-chip memory caching scheme has been reused for the recently released Xeon Max series of processors.
Because Phi’s performance is convincing, and because technologies pioneered with Phi are still in active use, it is undebatably unlike Itanium in significant ways. Just like a GPU, “specialized hardware” is not synonymous with “bad hardware.”