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.
1) It's as big as Twitter was back in 2011, and it's growing as more people use it.
2) I don't have an answer for this, because it would take considerable effort to get web designers to include mastodon links in their social media interactions.
4) Propaganda is almost nonexistent here in Mastodon.