1. People didn't actually use it to buy stuff because they want to comparison shop.
2. The devices were sold at a huge loss.
What I think has changed is that Amazon now has a lot more "products" to buy and devices that make the shopping easier. If you can ask Alexa to "order X things from the Whole Foods nearby, but prefer brands I've shopped in the past" and then you're able to confirm the order on a screen, then have it delivered to your house within a few hours, that's a much more compelling offering.
I wonder if /how that will change now after this.