For now, at work, it's just some parts with AVX-512, some parts with AVX-512 that we can't really use, so we should use AVX2, and some parts with NEON and SVE. So the implementations for SSE basically are a courtesy to outside users of the libraries, and there are no RVV implementations.

If we were already depending on highway or eve, I would think it's great to ship the generic SIMD version instead of the SSE version, which probably compiles down to the same thing on the relevant targets. This way, if future maintainers need to make changes and don't want to deal with the several implementations I have left behind, the presence of the generic implementation would allow them to delete them rather than making the same changes a bunch of times.