As someone who doesn't use twitter primarily because of this "everything is retweets" phenomenon, I wouldn't say that means no one uses it. Twitter is an idea propagation platform. It's not about everyone just sharing and consuming original content; what good is original content if only direct connections ever see it?

Twitter's most important aspect is watching ideas spread, even if it's misinformation, even if it's a cat video, even if it's a big game of telephone and the meaning gets corrupted in transit, you get to see what resonates with people. And that is very valuable.