"Modern advertising and branding is based on emotion and vague ideas. The same algorithms to target online ads have been used to influence politics (see cambridge analytica)."You're right, advertising and branding is, as you say, based on harnessing one's emotions, however an integral part of that process is also involved in converting those initial 'vague ideas'/notions into a solid worldview and it's this newly-developed worldview that causes its recipient/owner to actually believe in or act upon the idea. In essence, this is the basis of all propaganda; and, as we all know, in its most extreme forms it's both pernicious and very dangerous.
Probably the best—and certainly the most infamous—explanation of how one's worldview can be changed by carefully planned propaganda comes from a 1928 speech titled Knowledge and Propaganda. Tragically, this succinct and simple to understand speech comes from one of the most notorious and despicable persons of the 20th Century, and we only have to look to history to see how devastatingly effective the contents of this short message turned out to be: https://research.calvin.edu/german-propaganda-archive/goeb54....
Naturally, the advertising industry would want to dissociate itself from this document as much as is absolutely possible but I'd bet many dollars to a brick that many in the advertising industry have read it secretly and understand its message extremely well. Why? Because it has form—when actually implemented its message turned out to be so overwhelmingly effective.
In a free market capitalist economy, advertising is seen and considered as being beneficial, and at one end of the spectrum, it probably is, but as we've seen recently, at the other end it can morph into dangerous propaganda—and, unfortunately, there is no clear demarcation point to separate the two. Given the fact that trillions of dollars are now tied up in advertising, and that serious things have been done in its name (Cambridge Analytica and those other recent assaults on democracy), I reckon it's now time that we stopped pretending that advertising and propaganda are separate entities when clearly they are not.
In my opinion, if we viewed them as both one and the same entity and then set rules accordingly, then we would have some hope of making progress.