Is the tendency for devisive content to be promoted a quirk of certain social media platforms, or is something more inherent? I'd argue that people are more likely to click on something if it presents a message of, "You are under attack!!" as opposed to say, "Firefighter rescues kitten from tree!" because the former invokes more and more powerful emotions. Brains are designed to seek out and pay attention to threats, and I think even something like a print newspaper is going to be subject to that incentive, at least to a degree.

The other question I have is:

What we need to do is take away the power social media companies have to influence the types and quantity of information we receive.

Do you mean through state regulation, or just consumer choice?