So here's a thought. You know you're an impulse shopper. You can't go to the grocery store and buy 1 thing. You go to Target for detergent and come out with detergent, sponges, Swiffer cloths, oranges, cat treats, steaks, a coffee mug, and candy (or if you're me, you probably got all that but forgot the detergent and the cycle starts over when you go back to get it). You've recognized the problem, but solving it (be it via budget, shopping lists, envelopes, or whatever) is still a work in progress.
So say you run out of laundry detergent, but there's nothing else you need at the store. You hit your little Dash button and here comes your laundry detergent--completely without the temptation of any other items (be it in a brick 'n' mortar or on Amazon--digital shopping carts can be even more dangerous than physical ones). So you have your laundry detergent (which--if your memory is anything like mine--is not guaranteed even if you do go to the store), and you haven't blown through $50 on crap you don't need. Mustachian win-win, I'd say.