I would be very happy if we lived in a world where a code using SIMD instructions and hand crafted cache-blocking and threaded code was a "naive implementation"

I would be very happy if we lived in a world where a code using SIMD instructions and hand crafted cache-blocking and threaded code was a "naive implementation" but we are not. a "naive implementation" is a simple nested loop. The rest are complex and they become even more complex when one tries to implement them in a way which compile efficiently on multiple CPUs (from different caches to different architectures). Interesting article but the authors' conclusion is completely misguided.