For me, it is difficult to pin down what exactly this type of thing should be. Is it purely for data migration? ie: I am closing my facebook account and want t

For me, it is difficult to pin down what exactly this type of thing should be. Is it purely for data migration? ie: I am closing my facebook account and want to extract an archive copy of all my contacts, posts, uploads, etc Is it better to function as a direct transfer? How could it possibly make sense to transfer my old hackernews comments to my new facebook account? The more I think about it, the more I just come back to email. Not necessarily the specific implementations, just the high level design: From any domain, I should be able to send a direct message to a contact in any domain. They should be able to view any basic[0] content I post (text, images, calendar) and respond in kind with basic content regardless of the domain either of us use. I'm not sure that fully-federated-everything is the best answer and I would expect most reasonable implementations to include "Sign in at facebook.com for the best experience" or whatever. I can't personally imagine the ideal system yet but I assume it must be somewhere in the unmapped middle ground between Facebook/Twitter/Apple silos and thousands of impossible-to-trust sloppily-federated micro-domains hosted by random individuals. Edit: As an aside, the issue of authentication seems critically important with no clear designs that would provide a secure and usable solution. Though, the issue of account name squatters does already exist, it is relatively manageable with so few domains and no inter-operability between domains. [0] This concept of "basic" data seems to be more-or-less captured by the "verticals" described here https://datatransferproject.dev/documentation https://datatransferproject.dev/documentation