Funnily enough, intrinsics have become almost trivial to write, with agentic tooling. I used to be an ISPC advocate but now I'm finding myself gravitate to direct use of intrinsics with bespoke dynamic/runtime dispatching more than ever.
In C++, one can also have portable intrinsics plus simpler runtime dispatching using our Highway library :)
Yes, Highway is pretty nice but also quite elaborate when it comes to dealing with multiple vectorized versions and dispatch. The macros burn my eyes still.
I do think we've converged on the best that's possible in C++.