Earlier quoted context omitted.
> "ownership of your own social graph" What would that mean? > If these platforms were forced to act more like email Who decides who's "following" who? Say I decide to use a competitor. Do I then get to "take" my Twitter followers and can still broadcast to them on Twitter from a different app? Under what conditions can Twitter block your activity? Either they will have to let a lot of spam in or they'll have to ban…
All this is actually worked out in some detail (search keywords federated/indie web). Check out the PubSub model, and the ActivityPub protocol as an example, and Mastodon as a working proof-of-concept. As a starting point, imagine email & RSS and work forward from there. I'm not saying it's trivial, but it's also not insurmountable.
The standard doesn't define all that much. Arbitrary undocumented JSON fields are perfectly fine and used heavily. Just following the standard you wouldn't get too far, would need to follow Mastodon's implementation to be truly compatible [0].
Many instances have already banned each other, some client apps have outright hard-coded blacklists in. So again would the government forbid that? But then what do you do about unruly instances?
The whole model IMO is pretty wrong in favoring instances over individuals. Twitter is a free-for-all, this model is completely different in optimizing for small groups of like minded people.
Secure private DMs are pretty much impossible in AP.
Rate limiting, spam protections etc are left completely up to the implementer. So would the government define that under an anti-trust scheme?
Now if one considers it to be just some low-level building block for distributed social then okay, maybe it's fine. The idea is basically social-related stuff in JSON over HTTP. Okay. But it doesn't really solve much of anything in practice. It offers a strictly worse experience in name of decentralization. This is exactly why I'd be afraid of the government stepping in and forcing these kinds of decisions on companies.
[0] And then it only gets you compatible with other Mastodon-style instances (and most seem to use the exact same implementation, just different themes). There are other ActivityPub apps that operate under a completely different UX/UI scheme. Which is both nice and weird in that the standard has obviously been written with Twitter-like stuff in mind.