Different apps can converge on the same posts
A feed does not need to copy another platform to begin looking familiar. Many recommendation systems are trying to solve a similar problem: predict what a person is likely to watch, like, comment on, or share. Those actions become signals the system can use to rank the next batch of posts.
Across apps, the signals may differ, but the incentives often point in the same direction. A post that holds attention or prompts a reaction is more likely to be shown to additional people. If it performs well with one audience, the system can test it with others—and a successful post can spread far beyond its original circle.
The feedback loop favors proven formats
Ranking creates a loop: a post gets shown, people react, and those reactions help determine whether it gets shown again. This can give already-popular material an advantage. Creators, meanwhile, can see which formats travel well and make more posts with similar hooks, pacing, or topics.
The result is not necessarily identical feeds. Each app still has its own users, ranking rules, and supply of content. But when platforms reward similar forms of attention, they can independently elevate the same kinds of posts: instantly legible, easy to react to, and likely to keep someone scrolling.
Why chronology would look different
A chronological feed mainly answers, “What was posted most recently?” An engagement-ranked feed asks, in effect, “What seems most likely to hold this person’s attention now?” That second question can repeatedly surface proven viral material, even when it is not new or especially representative of what people are posting overall.
So the resemblance comes from shared pressures, not a shared master feed: when many systems learn from reactions and compete for attention, they can steer creators and audiences toward a common set of winning patterns.
