12. You have to leave an unsolved problem in the hands of the users, so that their interaction with the network takes the form of exploring/looking for things, and solving the problem themselves. It's a center of identity and intrigue that will draw people in.
I don't think Mastodon needs to have a "universal" search or solve its fragmentation problem. That can be what the users do: curate, discover, explore. Letting them exist in space of unsolved problem also gives vision of possibilities.