I would, because the targeting creeps me out entirely. Instagram were so good at it that I deleted the app. In the old days, you stuck luxury advertising in rich neighborhoods and used demographics for broadcast and other media. That'll do.
Don't get me wrong, I'm not keen on getting tracked, either. But I can totally see that from a company's perspective, if you can make sure that only people who are interested in your product actually see the ad, that's better. You don't annoy people who aren't interested (not everyone in a rich neighborhood cares about a BMW ad, some already have a Tesla) and you increase effectiveness.
Because "better [for advertisers]" is a euphemism for "worse for advertisees".
> Why stop there?
Because it's deeply unethical.