[1] https://www.nytimes.com/2014/06/30/technology/facebook-tinke...
To my mind, there is something inherently wrong about the techniques used to sway opinion about products and services. They prey on our animalian reflexes and bypass the part of the brain even capable of consent. Marketing "should" (and I don't use that word often) be prohibited to use such tactics, and instead be an exposition of the product and service and any traceable, trustworthy qualifications bestowed upon it. Such a system is still hackable (selling awards for instance), but it's a way better alternative to marketing practices than what we have today.
Devils advocate, even us tech people don’t 100% understand the scope and reach of Facebook, what they are doing is unprecedented. It’s not like there could be really informed typical users.