I don’t think relying on Facebook for your entire countries messaging is considered “a solved problem”.
Relying on any one company is bad. But Facebook might be just about the worst.
Relying on any one company is bad. But Facebook might be just about the worst.
I would also by far prefer a more open solution, but between relying on Apple for your country's messaging to relying on Facebook, at least by relying on Facebook you have one less issue.