Your whole argument falls apart when one considers that performance needs aren't split just between SIMD + careful data layout and anything goes. C++ isn't use

Your whole argument falls apart when one considers that performance needs aren't split just between SIMD + careful data layout and anything goes. C++ isn't used only for generating the fastest possible code, but also to generate code with predictable performance, code that is default-fast and code that can be optimized without the fear of having to change programming languages to reach a performance goal.