I think the grandparent's post is blowing the issue out of proportion. Amazon Dash isn't a phone app because phone apps are really slow and difficult for this use (if you've ever tried to use a barcode scanner based on your phone's built-in camera, you know what I'm talking about), not because people can't understand that their phone can do more than one thing. It is true that non-technical people are probably less annoyed by redundancy, but we shouldn't presuppose that this product is actually redundant just because phones can eventually do all the same tricks. The thing is that phones can't do those tricks as well, so the separation is justified.