Anecdote here: Old school targeted ads helped me discover something i didn't know i wanted. I was watching a game of football ( soccer for americans), and during the halftime break there were ads I wasn't really paying attention to, and per tradition, they were oriented towards males. There was an add for a decent looking multi-purpose electric razer that came with all sorts of attachments for different body parts, including head. I bought it and use it frequently, including for cutting my hair ( which has saved me hundreds of euros compared to going to a hairdresser) and beard.

So, sometimes a targeted ad can be useful. A contextually targeted ad can be useful too ( e.g. cooking utensils / supplies on a a recipe site).