Advertisement is unquestionably a net positive for society and humanity. It's one of the few true positive sum business models where everyone is better off.
It's the exact opposite. Advertising-based model is why the poorest people in the poorest countries in the world have had access to the exact same Google search, YouTube and Facebook as the richest people in the US. Ad-supported business models are the great equalizers of wealth.
The whole "attention economy" is a cancerous outgrowth of advertising. When the customer is paying with their time instead of money, wasting their time becomes your goal. The impact on society is hard to measure, but it's not nothing and I would argue a net-negative.
Advertising is a necessary thing and can be beneficial to everyone. I have something to sell, you want to buy that thing, and know you know I'm selling it. Win win.
On the other hand, the advertisement and associated privacy-brokerage industries are a very different story
"unquestionably"? Given that vast majority of ads are for harmful self-destructive projects or misleading or lying or make place where they got spammed worse... Sometimes multiple at once.
Spam alone (also advertisement) is quite annoying and destructive.