Let me be clear about my claim: tailor made solutions to each problem will almost always be faster than generic solutions. Do you really disagree with that?
I disagree with it in the sense that I disagree with the statement "A human will always be able to write the same or better assembly than a C compiler, because humans can learn the compiler's tricks and make optimizations which the compiler is not allowed to make." It's a true statement, but it's so detached and irrelevant that it hardly matters.
Generic code has proven itself time and time again, even Go caved in and supported it.