I'm not sure the takeaway here is that anybody's conferring personhood on Alexa. I think they're just pointing out that there's meaning conveyed in speech beyond just the content of the words spoken. Regardless of what words someone says, saying it in a whisper implies something about the volume that other parties should respond with. I had a coworker with laryngitis last winter, and I found myself unconsciously lowering my volume to be closer to his raspy voice. Tone and volume of speech can communicate a lot; why not allow a spoken word interface to leverage that extra information?