When the shortlived Great Migration to Mastodon took place last year, it was terribly cumbersome if you wanted to move instances — you would lose all of your friends again, at which point you’re required to somehow alert every account which follows you and expect them to go through the steps to add your new account. This is just too messy and for people who have spent years building their perfect social net, this is a pretty severe roadblock when one is forced to choose between a new instance with better culture but losing years of work connecting with interesting people.
Also note that email is federated, yet the majority of users have congregated around Gmail.
I predict that the same thing will happen with Mastodon, and that is not the type of future we should have.
Instead, I urge everybody to use P2P/decentralized networking, where even though there might be strong/reliable federated hosts, YOU fundamentally control your identity and it does NOT belong to a federated host.