Signal focuses on security and privacy above all else, which they don't think a federated model can do well. Case in point, XMPP in practice is less secure than

Signal focuses on security and privacy above all else, which they don't think a federated model can do well. Case in point, XMPP in practice is less secure than Signal but has the advantages you mentioned. The other common anti-federation argument is spam/reputation, which is basically the reason email is becoming more centralized unfortunately, though it still survives.