Users quickly learn that "we don't do that here", and stop.
Why, then, does the outrage porn rise to the top of the Reddit home page?
Because it measurably increases sales in a huge way right now.
To use a baseball analogy, how do you tell a juiced to the gills superstar that steroids are actually hurting their long-term outlook?
There’s no way to show Barry Bonds a future in which he’s shadow banned from the hall of fame and unmentionable even on his own teams broadcasts.
The change will come either with regulation or when a new, better system comes along and steals their users.
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.