Two main reasons, in my view : - It's way more profitable for the advertising platforms (that remains to be seen for the advertisers, see point 2) because you

Two main reasons, in my view : - It's way more profitable for the advertising platforms (that remains to be seen for the advertisers, see point 2) because you multiply/combine the number of different audiences infinitely or so => more campaigns, more budget... - The user engagement metrics (clicks on your ads, return on invest, etc) are waaaay sexier with targeting advertising. It's pretty logical, since people you adress your content with are much likely to be at least a bit interested. Privacy and user's anger might effectively have an impact, but we can also suppose advertising platforms will adapt anyway.