Mastodon has two big problems. It's not just the network effect but also educating the users on how to use a federated social network. It's easy with a technical background to overestimate how easily people will understand that, let alone care about it.

Here's mainstream news trying to get people onto Mastodon, and even this is in the "tech" section: https://www.nbcnews.com/tech/mastodon-social-media-twitter-r...