I agree that the word “why” is perhaps not the best choice, but it really stands for “what is the physical mechanism for”.
Anyway, what you describe is engineering, not science. A scientist explains the mechanism by which a stone ax can kill a mammoth. An engineer uses this understanding to design a better ax. A craftsman builds the ax. A warrior takes the ax, kills the mammoth, and wins the girl.
I agree that the word “why” is perhaps not the best choice, but it really stands for “what is the physical mechanism for”.
Anyway, what you describe is engineering, not science. A scientist explains the mechanism by which a stone ax can kill a mammoth. An engineer uses this understanding to design a better ax. A craftsman builds the ax. A warrior takes the ax, kills the mammoth, and wins the girl.