[lunula]

You can use other messaging services. But the one you use may get bought up. They are fickle.

Why isn't there a popular p2p solution to messaging (other than email)?

[ffggvv]

Email is not p2p. And building an encrypted p2p is technically hard. Building a p2p even without encryption has UX problems. The other problem is how to make money from it? What's the incentive (for a private) to build it?