> If Facebook was completely open source, people would create alternative servers compatible with the original implementation and steal the users who disagree with the surveillance. Only the proprietary walled garden keeps Facebook alive now.

It's called network effect. Just because it is open source won't magically make it federated and it certainly won't - magically or otherwise - convince a majority of users to leave their friends behind for a new network.

>> Afaik the only thing that really helps if you want to keep communicating over the internet and can't trust anyone is E2EE (End To End Encryption)[0] (and more opsec than almost anyone is prepared to deliver[1]. But how can you trust that a proprietary software actually implements E2EE?

> You need the source code to verify that.

That doesn't help unless you have a verifyable build process.