Twitter used to have a vibrant ecosystem of clients, most of them working better than the official app both on web and mobile. Twitter was able to kill their third party app ecosystem with their paid API changes and lived to thrive as a company till recently.
The reality is, you need a good cohort of content and users to move who can sustain the content, moderation and discussion. Just moving Apollo users doesn't ensure that. There are other good third party clients like Relay etc as well