Apparently in 2018 Facebook turned off the algorithm for a small percentage of users:

"What happens if we delete ranked News Feed?” they asked in an internal report summing up the experiment. Their findings: Without a News Feed algorithm, engagement on Facebook drops significantly, people hide 50% more posts, content from Facebook Groups rises to the top, and — surprisingly — Facebook makes even more money from users scrolling through the News Feed.

So in summary:

1. Users spent more time on social media
2. Facebook made more money since more time/scrolling means more ads
3. Users were less happy

I've been banging this drum for a long time, including In Defense of the Algorithmic Timeline in May 2016:

Not everybody agrees that this is the best way to go and they will tell you that an unmodified chronological timeline is the objectively better way to do things, but I think they're wrong. As long as they're able to do it well, I want my social networks to curate the best stuff for me. I don't have the time to obsessively curate my following list to have exactly the right number of posts in my timelines every time, and I'm not going to spend all day reading every damn post in the timeline of each app on my phone.

I think people see this argument as a battle between reverse-chron timelines with nothing but joy and algorithmic timelines full of misinformation and rage, but I think there's plenty of gray area where we can do better.