These platforms have hyper-optimized their products to show as much stuff as possible that people will engage with (share, click), so that they also engage with ads and stay active.

The problem is there is often some time when there is no news. No news isn't interesting, so it doesn't get shared as much as "news". Take the moments immediately following a disaster. Two types of news articles will show up:

"There was a shooting. We don't know anything yet, but we will keep you posted". Boring.

"We know who the killer is. Bobby Bobertson done it". Woah!

Now imagine you are a heavy social media user. You don't want to stay silent on such a big news story, so you want to share something showing you are engaged. Which story do you share?

(edit: removed duplicate "the problem is")