If we want open social media to be a meeting place for people of all class backgrounds, races, religions, and from all over the world that means it'd need to be "popular" ... it'd need to be something that could work for people without a desktop computer who mostly use the internet on their phone.
It'd need to be free for most users and easy to get started. Consider how threads and blueSky have outpaced the fedi mostly due to their focus on these use cases. 3/