New Delhi, Sept. 22 -- When I used to wear the hat of a marketer, I had a simple if exasperating mandate: understand our customers. Real, unpredictable, messy humans with their peculiarities, their irrational loyalty to competitors and their occasional acts of rebellion against ad jingles that got stuck in their heads.

I had sent armies of market researchers to stalk potential customers in malls and kirana stores, organized focus groups with freebies for participation and wired consumers to eye-tracking machines. I called this measuring sentiment.

Fast-forward to today, the AI era, and the marketing cosmos looks like it has been hijacked by a mischievous sorcerer. Consumers are still human, yes. They still binge-watch serials, pretend t...