I've been asking people around me what is holding them from using Mastodon (even after some of them joined), and I got 4 reasons:
1) Not many people here
2) Can't find people here even if they're here
3) It looks very complicated, especially the instances thing
4) Doesn't seem too different from Birdsite so why bother
For people to adopt this platform, these four points need to be addressed. And that too in ultra-simple non-nerdy language.
3) Imagine 2 Monopoly boards where all the spaces are owned and developed. Twitter is the board where all the spaces are owned by one person, and Mastodon is the board where each space is owned by a different person. In the Twitter board, there is no place to go to, because all spaces have the same crappy rules. But on Mastodon, you may prefer certain spaces and stick around there, if not, it's easy to move to a different space.
@Memeghnad
4) Propaganda is almost nonexistent here in Mastodon.