Sorry, bullshit. I often mumble, and naturally ask Siri things. She gets it right 95% of the time. I've never felt the need to "speak loudly" or "learn commands", beyond having a rough understanding of what Siri can and can't do, just like any voice assistant. It's not perfect, and never will be (neither will any voice based system) but has made enormous improvements since launched. Please, don't use your odd beliefs as fact.