Other way around. They're not paid, so they want to keep the amount of unrelated contentious bullshit on their subreddit to a minimum. I've been a default sub mod and I know how much of a firehose that is. The simplest solution, and the smallest amount of work in total, is to nip unrelated discussions in the bud, delete entire comment trees, and lock the comment section entirely on a post that is (or is looking to) go south.
Users quickly learn that "we don't do that here", and stop.
Outrage has always traveled faster than dry factual information. This isn't a new Internet phenomenon. You can see it in action all the way back in Greek and Roman history as well. It's an inmate feature of human psychology, not a new invention by reddit/Twitter.
Yes, and the fact that these platforms haven't taken steps to prevent abuse of the cheat code in our psychology means that they find the benefits of outrage to their bottom line outweigh the "unmeasurable" costs such as damage to society and the hollowing out of their platform.
> Besides, if our brains are designed to zoom in on certain signals, is it rational to expect technology to somehow prevent this?
Technology can mitigate it (by suppressing the signals, offsetting the effect) or exploit and exacerbate it. The former is often socially useful, but the latter is usually the path of least resistance to profits, and capitalism isn't a system whose incentives optimize for social utility.
Users quickly learn that "we don't do that here", and stop.