not arguing against you, but DMs have a super power; it is easy to keep censorship resistant, because it is a small world. all you need is a protocol, servers and sovereign identifiers to migrate between servers while keeping your ids.
another superpower; people actually tolerate when chat history is lost due to losing encryption keys.
I would say we should focus on DMs more than social since it is easier to get done, but Matrix is good enough so not very urgent to reinvent