> I have difficulty understanding how a reasonable person can come to such a conclusion.

The applications are very niche. Compilers are usually not smart enough to utilize SIMD, it is a hit or miss. And in order to implement properly efficient SIMD algorithms you need experts that are rare. Furthermore many algorithms that work great with SIMD work even better as compute shader on your run of the mill cheap iGPU.

The application of this article is the best example how irrelevant SIMD really is: How many Terabytes of UTF8 are you converting to UTF16 per day? probably zero.