I don't see why you couldn't just go back to more loose-grained targeting based on demographics. For instance, the adds I hear during the podcasts I listen to

I don't see why you couldn't just go back to more loose-grained targeting based on demographics. For instance, the adds I hear during the podcasts I listen to are largely relevant to me, because they're targeted towards the type of person who would enjoy that content. Nobody minds this, because they don't have to collect personal information to target this way. I think it's better for everyone if businesses were incentivized to create spaces to delight and engage high-value demographics, rather than just manipulating users into spending time on their site long enough for an ML algorithm to find the right add you're willing to click on.