Earlier quoted context omitted.
Targeted ads are much more effective at influencing you, so you avoid more unwanted influence by blocking a targeted ad than just an average ad. Targeted ads are insidious - as natrius says, they prey on your psychology. By comparison, non-targeted ads are generally just an eyesore.
Your entire position depends on the unstated assumption that it's wrong for someone else to convince you to buy their product. And that sounds pretty absurd. As for targeted advertising, seeing ads that are relevant to your interests instead of seeing unrelated ads does not seem wrong at all. As long as you're being advertised to, isn't it good to have those ads actually be things you might care about? The part that'…
Psychologists know that humans have certain exploitable weaknesses. I mean, think about any relationship. You become vulnerable when you expose yourself, and so a person has to earn your trust such that you expose yourself to them.
Today, advertisers have made you vulnerable without actually earning your trust. You could argue that "by using Facebook you're saying you trust them," and you'd be right... If humans all had the capability and willpower to understand systems as complex as ad targeting... One of our worst exploitable vulnerabilities.
Put another way, I would say that it's ethical for a team of scientists to sit down and interview you about everything you love/fear/want/need for the purpose of helping you to find more people like yourself so you feel less lonely. I would say that it's unethical for those scientists to radio down the street as soon as you walk out the door to tell street vendors to start hawking goods that play at your insecurities.
Not all advertising is based on exploiting people, but the most effective types are!