Twitter succeeded because (and I'm not au fait with the details of how exactly) they managed to onboard a lot of high profile users from a variety of different walks of life. Everybody else came to hear what they had to say. This must have been a huge amount of work, and not something that's talked about much and I can only presume you'd have to do something similar to mount any kind of credible opposition. That's a lot of work for people who's prime motivation is chasing dopamine hits.

EDIT can't reply to below cause I've used up all my commenting credits for now: My word selection (au fait) relates probably to cultural context. This is a phrase that people around me use frequently. Sorry not trying to be obscurantist or anything. I just have a life outside the Internet where people talk in non-Internet ways.