The trouble is people want to smoke and drink, too.
The human mind is more easily exploitable than any computer.
Of course people want to see divisive content. Divisive content is engineered to trigger large emotions, which humans naturally respond to. That's what heroin exists - it feels good. Really, really good. Of course you don't need only good feelongs, bad feelings can shape behavior too.
The problem comes in when we start shifting from making products that simply cause these behavior changes to instead making products engineered to elicit the biggest response possible.
Its very easy to do, too. Want to sell more cigarettes? Add butane to the wrapping so it burns better. Concentrate the nicotine. Do all the obvious stuff. The more bad you make it, the better it will sell.
Same thing with, say, Facebook. Want people to use Facebook more? More doomerism, more lies, more misinformation, more Jesus Christ, more click bait. People want the addictive stuff, that's why we call it addictive.
So yes, social media apps without these tools are unpopular and generally fail. In the same way a nicotine-free cigarette would fail.