That’s might be an option too, I guess, but in some situations it’s a different question. If I make a mistake and you ask “how”, you might just get more details. If you ask “why” I might respond with “I was tired”, which doesn’t really imply teleology. As I understand it почему would be more specific to cause rather than just means, but then again my Russian is pretty basic. The word “how” would be как, and it even works as an intensifier the same way.