I honestly don't know how to be more clear. It's called a social graph. The most important thing about a social network, above everything else (for normies), is having lots of users. Cory and Molly both know and understand that if they left Xitter, they would lose access to a substantial amount of their audience, so they both stay, despite being some of the platform's harshest critics and the biggest supporters of it's alternatives. That's the answer to the question "why would anyone use it?". The social graph.