i keep wondering this myself, so many places are still prominently presenting the xitter button to follow them on,like it's a totally normal thing to do. it's fucking bizzare imo.
As opposed to what? It's where the people they follow post. Why would they leave for somewhere that doesn't have any content they care about? It's like asking who the fuck is still on reddit. The answer is the enormous shitload of people who just want a steady feed of the same content they've always consumed.
A lot of researchers whose built a network on it. It's not as easy as it seems for them to switch to another social media. Each connection is important to know about new articles when they come out.