> But they'll clearly build detailed profiles on every preference or product you mention, your age, your location, etc. so they know what ads to show you?

I'd guess an advertiser can ask OpenAI "show this ad to people between 18-34?", and then certainly anyone who clicks and then buys they'd know is 18-34 since they knew they came from the ad. But that there's no way for advertisers to directly buy a list of folks who are 18-34 but don't buy something from their website.

That's how it often works and seems in the spirit of the sentence you quoted.