Seems like choosing a server stops a lot of people from joining Mastodon. If Mastodon wants to grow the community, it would be a good idea to add an "I don't care--pick a server for me," button to joinmastodon.org and then point new users to servers based on language spoken.

This was a barrier for me when I joined a few years ago. I can't remember how I decided on this one. Maybe because I discovered it was run by Mastodon's founder and I figured it would be more likely to be stable.