But a post on Facebook looks different from a post on Twitter. Could they really share? Could you write a regulation where it makes sense that they're different?

Maybe you could. Twitter and Tumblr seem to be about the same modulo the length. Isn't the advantage of Twitter its shortness? Maybe we'd discover what the advantage of Twitter is.

And perhaps Facebook is the same just with better networking features. Maybe we should try to write federated Facebook and Twitter clones to prove it can be done.

The only difference is that a post on Twitter has artificially limited size. This is a restriction imposed by Twitter and as such could be handled by them - for example by showing a short summary + a link to full message for posts that were imported from other networks.

I would think this would be _really_ hard. So many of the simple features that make up a social network are incredibly complex on the backend. Things like hashtags, searches, recommended friends. Are giant specially indexed and formatted databases. If all social networks did was send messages that would be easy but how do you do a newsfeed amalgamating multiple companies? Does everyone have to use the same algorithm for newsfeeds? Who’s comments come up first, what does search look like? How about spam control, are you allowed to block posts from an unregulated social network? Do you all have to have the same content guidelines and ToS?

Requiring reasonably-formatted downloads of "friends" lists would go a long way toward making switching networks frictionless.

Whether or not such a requirement would be good for privacy is an important question.

Obtaining your list of friends is not the factor that makes switching social networks unattractive, it is the friends themselves.

The list doesn't help if your friends aren't on the other network. HN loves to come up with technical solutions to the problem of Facebook when it largely isn't a technical problem, it is a social one.

It makes a huge difference whether you can pre-populate a new network with a list of your friends, as it makes your friends' discovery possible.

Imagine, which Google+ launched, how things might have gone if 5% of Facebook users could have moved their own social graphs to G+ with two clicks of a mouse. If everyone had 100 friends, and those friends were uniformly distributed (all stark simplifying assumptions), then a huge fraction of the global social graph could have been moved to the new network by a small fraction of the users.

But you can't mandate a business model/technology. SS7 and IP aren't legislated worldwide, they're in place because it is in the best interest of telecom companies to be able to interconnect.

Social media has no such incentive, so how could a regulated federated standard work? Even if it could, who would pay for / provide the development? The social media companies certainly wouldn't (https://xkcd.com/927/), and governments wouldn't for largely the same reason.

perhaps federated protocols for all social media.