Threading
I love threads. Not the social network, but the concept of having a chain of thoughts. (Maybe that’s why I like to use Gibberish for drafting).
I think the best invention that social media sites like Twitter have is the threaded view, where short notes can be chained together.
In a way, my Zettelkasten is also capable of doing that, but replying is a bit harder, since we have to chain notes together somehow.