1. Going to a mobile-first website or app.
2. Clicking a link.
3. Typing in your new e-mail and password.
4. Being able to add anyone in the world as friends.
It cannot be about local "hubs" vs the global "public" / federation, being forced to make that distinction would feel like a step backwards for the users. It can be distributed in the back end, but not in the front end.
It also needs to look beautiful.
If you want to build a reddit, you'll never end up with a facebook, that's just reality, the target demo is completely different.
Certainly anecdotal evidence, and I'm inclined to believe the largest user base may still match your description, but personally I feel like you're describing 4chan, not Reddit.
(1) Everyone's identity is their email.
(2) The person whose email you're typing in has already signed in to the service (or meta-service if it's a federation), and agrees to communicate with you.
If you squint just right, this exact thing already exists; it's called email, and adding to friends means adding to a mail list.
I wonder why there were no (known to me) attempts to actually use the email infrastructure (fast, reliable, ubiquitous, near zero-cost) to distribute social network updates. It could use a custom pretty frontend app that makes posting or reading updates easier than e.g. gmail.
(As a bonus point, the actual emails can be reasonably human-friendly, as an extra archive of all of your updates.)
It's not necessarily fast, delivery may take only 1 second but I've also had email take days until it was delivered successfully.
Reliability is meh, it has some resilience to services being offline for a bit, so I'll give you that.
The near-zero cost is also not quite true. It's only true if you sell your data to the provider of your choice, gmail or yahoo or AOL. If you want privacy on email, you'll have to pay for it, otherwise you pay by other means first.
There is a chat app that uses email to function, it also features encryption but IIRC the userbase is very small and last i tried it for testing, it did quite spam my inbox.
How do you stay logged in if there's no cookies?
It also looks like they try to do too much. Cure-alls cure nothing (thanks for the quip, Sawbones podcast!)
"We don’t track you personally and we never sell your personal data. Here is what we track: we track how users use our site in general so that we can make it better. We are monitoring traffic, usage activity, site performance, and we use general analytic tools so that we can improve your experience. We do not associate any of this data with you personally. We never sell or share your personally identifiable information unless required to do so by law."
In my mind, when I read HN comments, I assume all the people who post here know what I know and more but then there's a post that comes along that reminds me of the sheer gulf of knowledge that can exist even between people on such a speicalized site as this one.
