TL;DR: The current Mastodon-signup is only removing the confusion of users on first glance, because it either hides the server-choice altogether, or leaves them with a choice that is impossible to make at this point of their Mastodon-journey. Instead, it should introduce them to decentrality on a lower scale, with a handful of handpicked servers to choose from, such that the decision makes sense to them and shows them the merits and fun of the concept instead of scaring them away. Ideal would be to give them a sense of agency. Then, chances are higher that they consider migrating again in the future and eventually internalize it as a permanent option of the digital world.
I used “microblogging” earlier as a stand-in for “Twitter-like,” and I shamelessly pulled that terminology from the kbin interface. It’s accurate, but I don’t know that the term is sufficient to gain popular traction - and I certainly do not pretend to be the person to dictate what the terminology ought to be.
Now that I think about it, the core of social media of all types is “someone posts a thing” (whether that thing is a link to something else or original text content), and other people comment on it. YouTube, Xitter, Reddit, slashdot, fark, etc etc. The display format, post and comment organization, tagging options - those are all ancillary.
Federation via ActivityPub introduces a wholly new aspect to social media by separating the client application from the content accessed therethrough. I, from kbin.social, can see and interact with content posted by someone originating from mastodon.social. Content is one thing, and client application another.
People do have familiarity with that kind of separation in at least one other internet functionality: email. People generally already understand that their web interface to their email provider allows them to send and receive email both within and without that provider, and that their mobile app is just a different way to access that same content. But SMTP email is old. Since then, the aim of content providers on the internet has been to capture and contain users, using existing protocols, which causes people to consider the provider and the content to be the same thing - because in so many cases, it is.
ActivityPub is a new(ish) protocol. Functionally, it is much more like email than it is like an internet forum of any kind. Extending this comparison, SMTP email is one-to-one (yes, there can be multiple recipients, but they are all themselves “ones”); ActivityPub is one-to-many. Yes, this is similar to traditional walled-garden forums, which are also one-to-many, but those walled-gardens restrict the “many” to “those who have accounts inside our garden.” Perhaps ActivityPub is more accurately described as one-to-very many or one-to-all.
It probably seems that I am avoiding your clear and plain question. Maybe I am, but I also think it’s important to consider the details of these as-yet-unnamed things in order to arrive at an appropriate and effective way to market them. Federated social media is a public forum in a way that previous internet forums have not been since Usenet. “Forumnet” seems like it could be workable. It’s definitely more descriptive than “fediverse” (a name I have never been very pleased by).
While it gets closer, that continues to avoid your specific question. I will need to put a good deal more thought to this, and must now direct my attention elsewhere. Watch this space.