Optimization is often about specializing, and therefore avoiding work you don't happen to need in your particular case. The article acknowledges that it's givi

Optimization is often about specializing, and therefore avoiding work you don't happen to need in your particular case. The article acknowledges that it's giving up some flexibility. It could maybe have been louder about it. This would be different if we were benchmarking to compare libraries or hardware or languages or whatnot, or even calling the new implementation "better" without qualifiers.