Given the realities of network effects and the observed tendency for a small number of social media platforms to dominate the market, this doesn't sound particularly realistic. More choice would indeed be great, but I highly doubt that'll ever happen with a product/service whose entire value proposition depends on everyone choosing the same one.

We need governments to promote federation, so we can have both choice and network effects.

To bad there's far less money in federation---it's "moatlessness" ruins the business proposition---so I don't know who will pay for this lobbying.

Wasn't this already "attempted" through the natural mechanics of the free market? Social media seems to tend toward monopoly (or at least oligopoly) due to the extreme realization of the network effect in this industry.

Here is a sampling attempts (though I'm sure the graveyard has hundreds if not thousands of members): Friendster, DailyBooth, FriendFeed, Google Buzz, Meerkat, Yik Yak, Vine, Google Plus, MySpace, Path, Orkut, ConnectU, ...

Sort of. Networks tend to lead towards natural monopolies. If you were my age, you had AOL IM friends, ICQ friends, Yahoo friends, etc.

The US had a phone company at the national level until regulatory bodies made a market.

Hardly realistic. People go where their friends are. This prevents scattering groups over many different social media. We had them in the 2000s, then only one made it to now (FB). The others that are big now (Instagram/FB, WhatsApp/FB, TikTok) are successful because IMHO are on a different medium so don't directly compete with FB and/or are used by a different demographic (young people don't go where older people are, same as for music.)