Is that a new thing? Seem to me that's been happening for like hundreds of years. I've worked at a PR firm and in a Newsroom. I've seen the sausage being made.
The key phrase was "micro-targeting" not "propaganda". Previously, if you put out an ad full of religious zealotry to appeal to fundamentalist Christians, you would risk turning off more moderate parts of your base. Now you can make sure only the "right" people see that message.