Alexa, order a 12-pack of toilet paper, a case of bottled water, and a bag of tortilla chips. Welcome to the new moment of truth. There is no shelf. There is no cart. There is no register. There isn’t even a laptop or mobile phone. There is only a talking cylinder on a kitchen table....

A new party has joined the purchase decision process. Enabled by data, digital assistants are poised to propel a new round of disruption coined “conversational commerce.” Consumers will at once become more accessible through individualized, contextual, in-the-moment messaging and less accessible thanks to the rational algorithm-driven suggestions coming from their digital assistants. Brands will need...