With mastodon/fediverse, you have a choice of numerous different 'twitters', rather than being stuck with the global twitter decision.
That's the part that interests me the most.
Which is why I (when I get around to it) will self-host my own ActivityPub instance (Mastodon? Pleroma? WriteFreely?).
That way, I decide what gets blocked and what doesn't. And since it's federated (assuming other sites will federate with me), I can still access the benefits of using fediverse resources, without being beholden to someone else to make such decisions for me.
From a longer-term perspective, ISTM that an ActiviyPub (AP) "user agent server" (UAS) which allowed individual users to federate with the resources of their choosing without having to "join" an extant instance, makes a lot of sense.
Rather the UAS would utilize your local (i.e., generated and managed/federated from your AP UAS instance) fediverse credentials and act as a proxy for you, communicating with the instances containing the resources you're interacting with and acting as storage/cache/server for the user's client apps.
This would make the fediverse even more decentralized and under user control. However, it would also make discoverability even harder.
Perhaps that's ActivityPub's killer app? A discovery app. Perhaps a protocol change to require a cryptographically signed summary/intro for each instance, along with with a searchable index?
It works a bit like "cell-phone number portability" in the US. You set your original account to point at your new account, and you tell your new account about your old account. All of your followers migrate to your new account automatically.
Of course, you could still get burnt if your host just disappears one day, because it can't point to your new account. So there's an incentive to use a well-run server with a good track record and a reasonable funding model, I guess.
Sorry for so many questions - do you know where can I read about the mechanics behind it?