I'd be kind of surprised if OpenAI were really doing this deliberately because a whole bunch of their execs come from Meta, and all those guys learned the hard way.

First: You don't want to leak information about your users to advertising networks because it's going to leak, get back to your customers, they're going to figure out you're doing it and get really angry.

But second and more importantly - it's a much better business model to collect that data for yourself, keep it in house and then you control how you use that data to target ads which gives you a massive competitive advantage in selling ads because you have unique targeting data.

The way meta does this now is the model, they don't give the advertiser a list of the people you're going to show the advert to, the advertiser gives you a list of characteristics they want to hit and meta decides who those people are.