I think Amazon were envisioning that Alexa will enable the next level of impulse online purchases. People simply saying "Alexa buy X for me" in their living room and it will automatically order X off Amazon for them.

But like... most people aren't THAT irresponsible with their money... yet. Even impulse buyers wanna see a picture and a price first before clicking order. Not just have Amazon pick god knows what at whichever price. And only find out when it arrive at your doorstep. There might be some people who use it this way but not enough to be a multi-billion dollar industry. Seems like a silly idea for now.