This statement is nonsensical. OMEMO for XMPP also uses parts of Signal's protocols, and yet both SimpleX and XMPP allow users to not give their metadata to a single centralized entity that is running a single endpoint with software they are unable to verify. Ingesting literally every user's metadata, while actively preventing them from connecting to users outside of their own service is pretty much the antithesis of bitcoin, nostr, and the rest of that list, message encryption or not.