(I do know that you can subscribe to individuals in other instances, but haven't done that yet.)
It seems like the ActivityPub protocol itself is designed from the "email server" perspective, but as different instances try to differentiate themselves and attract users, I bet the platform will swing more and more toward "web forum". It'll be interesting to see how it turns out.
Given the federated protocol, it's a reasonable expectation carrying around the same identity across instances.
alice register on instance "music"
alice wants to see what's up on instance "books"
Is the problem that the default behavior of Mastodon requires alice to register a new account on "books" just to see that instance's timeline?
For example this page shows the instance's timeline without logging in: https://mastodon.sdf.org/about
If you like someone's toots there, you can follow and message any user on SDF's instance from your account on any other instance.
As mentioned elsewhere, the only thing you would gain by creating an account on sdf.org is to have your toots appear by default in the local timeline of other sdf.org users.
Although it might be better to say that that's the manifestation of the real problem. The real problem is that I want to be able to talk about books sometimes, even though I'm a musician so I registered on the musician instance. If there's a way for me to have conversations about books, I don't care whether it's an "instance" or not. I just don't want to manage two separate accounts. (As an end-user, none of my end-goals mention the word "instance".)
For a federated design I'd assume the main difference among instances to be code of conduct/ToS.
More generally, my question is how do you meet people who are talking about something interesting to you? (Considering that there aren't many people using Mastodon yet, I don't expect to chat with people I know.)
The web forum/subreddit model makes it considerably easier to find interesting subject-based communities. This doesn't seem to be what Mastodon was designed for, but it seems like a good idea.
Wait, is this a thing? I've been using Mastodon for months and have never seen this in the UI.
there are a handful of proposals for doing SSO on fediverse, but it isn't super high priority since creating multiple accounts (alts) is a pretty common practice here.
Then you'll only end up with users that are willing to put up with that, and you will not get users that perceive this as a major inconvenience (I'm in this camp, and I suspect many, many others are too.)
I agree some platforms make multiple accounts hard to the point where you're registering multiple free email accounts, installing multiple browsers and using incognito mode, etc.
That is not inherently the case, and can be quite the opposite when allowing users to control multiple accounts is part of the software's design.
If you're forced to create one account per instance, there's no way to do something as simple as "merge comments from two instances into a single stream", which supposedly was the selling point of federated systems like Mastodon.
Obviously "topic" is the easiest way to differentiate instances today, but when was the last time you choose an email provider based on "topic" (or even domain name, for that matter)?
that said, you don't actually need multiple accounts to join conversations on other servers/topics. any account can talk to any other account on whatever server they happen to be registered on.
alts are more about identity than topics, in any case. in some cases, the topics you interact with are different, but that mostly depends on how much your want to differentiate your various identities.