I always figured there are some verticals where the value per acquisition was high enough, and the product narrowly-scoped enough, where it might make sense to microtarget individual customers-- profiling them individually and building custom messages for each of them.
The obvious target would be the narrow-scope prescription drugs-- all those ads that say "If you have XYZ-positive, PDQ-negative Exploding Sphincter Syndrome Type XVI with Sprinkles and Cheese Sauce". Presumably there are only a few hundred people with that condition in the country, but you're spending a lot of money to reach everyone else to try to catch them in your net.
Super-premium luxury goods might also fit there, but I wonder if the brand risk would be too high. Rolls Royce probably knows the 200 customers most likely to buy their new model, but it might not fit their brand to actually put together a campaign that seemed like they were actually TRYING to sell cars.
I think there are high value customers for whom this probably makes sense, but only if those doing the targeting make money from it. Right now you're the product, but the supplier is the one doing the targeting (or not) and the customer doesn't know enough about their potential customers to target. The suppliers don't really make money by effective targeting.
LLMs are useless in this domain.