> I think the idea is that ad tech makes ads more valuable?

This is what they want us to believe. I am pretty sure that in some years we will look at this claims from ad tech in the way that we see today the mid-century claims from Big Tobacco about the benefits of smoking.

> Maybe the future will be this personalization happens offline on the user's device.

It's already part of the present. This is exactly how Brave does the ad-matching. To make it perfect the only thing that I think is missing is for the user to have a way to train their own matching model, or at least to provide some kind of feedback about the types of ads that are relevant to them.

> And we all know that segment largely comes from particular geographies.

I believe that most companies already operate on the assumption that they will provide the service globally and lower-income markets are subsidized by richer regions. That is certainly true for any product that depends on network effects.

And for the products that do not depend on network effects, then the segmentation is likely to be a good thing. A more diverse set of companies, trying to solve the specific problems of different markets - instead of pushing for one-size-fits-all plans from big Corporations - is good thing in my book.