The categories are much to broad to be useful. I've been vegan for about 7 years. The internet thinks I like "food" and shows me ads for meat products all the time. Good to know I'm wasting the ad dollars of companies I think are bad, but I think it's gross and I don't want to see it.
And yet, I still think they can be harmful. Think of someone with alcohol use disorder who recently stopped drinking, or someone with BED who's decided not to keep junk food in the house. You don't think constantly seeing ads for alcohol/junk food would make such a person feel bad or even impede their progress? Why would that be the cost of them opening any website at all?
Or infomercials poping about anti depressants.
True anecdotes. Teenage girl tracked by video surveillance and profiled as being likely interested in contraceptives because she stood near the condom shelves for long minutes without purchase. With a good chance of being pregnant.
(Advertisers could mail to the household, yes. because she provided the supermarket with her address to get groceries delivered once)
A certain messaging app offered by a certain social media platform that mine personal conversations to profile users down to their emotional states. Those words you type in and send to your confident are put through real time machine learning.
Don't be too surprised you get an ad about chocolate right after you told your date about your favorite ice cream flavor, that's merely creepy. The obsene mental manipulation usually goes unnoticed.