Why do social media platforms copy each other

Social media platforms usually copy each other when they find that a certain feature is liked on another platform. They then copy this feature to stay in the competition. 

Social media apps have to constantly upgrade themselves to make sure that users stay satisfied. This means they can take features from other platforms if they are popular. 

Some social media apps sometimes copy a certain feature and try to execute it in a better way on their own platform such as Instagram copying the stories feature from Snapchat. See Why did Instagram copy Snapchat

When users get accustomed to a certain feature, they expect to find it on all other social media apps. In this case, copying a feature is done for the users' best interest.

Some social media apps copy each other in order to undermine the apps and show to users that some features aren't that special and can be added to other apps.

By picking and choosing features from several other apps, an app can have all the features a user needs in one app and guarantee their loyalty.

When a social media app feels threatened by another successful app, it might copy some of its features to attract some of its users.