If ads were merely about being informative, they would be boring. But ads want to manipulate, so they have to be flashy and appeal to your emotions.
They pollute your mental headspace, and have no place in a healthy society.
Let's ban billboards. And then let's follow that up with a general purpose ban on paid advertisement.
Advertising is how small and new companies can reach customers. It's how monopolies are broken. It's how progress reaches the masses.
Yes, it is willfully intended to change people's behavior. So are many of our posts on HN. That is an important purpose for communication!
And that makes all the difference. I am very happy to read that an HN commenter prefers one specific brand of car - assuming that this is an unbiased comment and the commenter was not paid to say that. On the other hand, if they *were* paid to say they like a specific brand of car, they are deceiving me! They are exposing my brain to ideas and associations that are inauthentic, and making me more likely to buy a certain brand of car even though that car cannot get mentioned on its own merits, and instead needs to pay for attention.
Also, I'm not sure I agree that "advertising is how monopolies are broken" - my read on the advertising industry is that larger companies today have a massive advantage over smaller companies, and that smaller businesses would be more able to succeed if advertising was removed. And the advantage more or less comes from the larger brands ability to afford to expose a larger number of people, and that exposure has superlinear effects on purchase behavior (because not only are you exposed to it, but your friends are talking about it, and their family is talking about it, etc).