[JohnTHaller]

Because the majority of social media users subscribe to more people/companies posting more things than the user could ever possibly read. Rather than users being overwhelmed with noise, getting frustrated, and possibly logging in less, social media companies come up with a way to show them enough content to keep them engaged and happy (and visiting the site/using the app) as long as possible.

[WalterSear]

If that was the real reason, then facebook wouldn't revert from 'chronological' to 'best' every time I visit the site.

The sorting algorithm is for the benefit of facebook and advertisers - and not necessarily by making me spend more time on facebook.

[AJ007]

Here is some speculation on my part, perhaps totally incorrect.

The three social platforms with non-chronological timelines now: Facebook, Twitter, Instagram, may all be seeing diminishing engagement from critical demographics (16-21.) Users log in less, so by "rewarding" them with the stickiest post when the do happen to log in, it appears to increase the retention of those cohorts.

Power users are following/friends with a lot of other users. If 1,000 - 2,000 people are followed there is a lot of noise. This also presents opportunities to completely bury the less sticky content, which also results in increasing ad revenue from publishers who got addicted to the free traffic (with "sticky" ads being rewarded with cheaper clickthroughs.)

The chronology complaint is interesting because reddit & hacker news have a similar sorting algorithm (voting, but with other complexities thrown in.) You log in, look, and log off. A compulsive user may check hourly.

There are definitely problems with dynamic sorting. Noisy producers may become more noisier because less of their stuff is being shown. Other users may not bother posting at all because they don't expect anyone to see what they posted. That audience is going to feel comfortable if another platform offers them a place they feel they are being heard.

Whatever the numbers show right now, the longer term retention cohorts have yet to be seen by anyone.

Despite monster ad revenue I am not convinced that Facebook has made a "slam dunk" on social media and will be the last man standing.

[mod]

Just make the old feed an option for "power users."

[jonesb6]

Except the real goal likely isn't usability, it's to show promoted content in with the real good content, ala Facebook, Twitter, Imgur, Reddit, Hacker News, the list goes on really.