"But the situation changes because sooner or later (potentially already happened) Twitter will eject actual community leaders and a community will need to reform somewhere else."

"Actual community leaders" is a matter of perspective though. "Actual community leaders" don't need a megaphone like Twitter, because they're already leaders that have an audience. Social media is a way to tap in to a broader distribution platform, and it seems appropriate that said platform would restrict that access to those that serve the interests of that broader audience.