Email is  a little different from social media since it is default private. You can all sorts of incompatible people with different values and interests using the same email provider, and none of them care because they are largely unaware of each other.

Social media is default public, and it seems we're struggling with how to best negotiate this space. It seems clear having a single, venture capital backed, host of a social network doesn't work. Heaps of abuse and other anti-social behavior abound, and users don't appear to have much influence beyond being the subjects of experiments. But it's not clear to me that only a dozen federated networks is the sweet spot. However, if it is, perhaps a larger set of federated networks is the appropriate starting point. They will get winnowed down from there? After all, isn't that how email progressed?