Last I checked benchmarking tools are assembled by compilers instead of by hand so the supposed Intel advantage there is already baked into the results.
Yup. But do you use benchmarks all day on your computer, or do you use applications? Which compiler are those applications compiled with?
Linux apps are clang & GCC, macs use clang, windows is clang, gcc, and Microsoft's compilers. AFAIK, icc is pretty small in market share.
You think msvc, gcc and clang all have special optimizations for intel? Intel only controls their own compiler, icc.
GCC has `-march` and `-mtune` flags for arch-specific optimizations. Just because the compiler is agnostic doesn't mean it can't have, or welcome, arch-specific optimizations.