I generally agree with this, but a problem I can't solve is: at what point does a "large group chat" become a "public channel"? If, hypothetically, someone is organizing a thousand people in balaclavas to turn up outside a business they want to intimidate, over Telegram or Signal, is that "private" or "public"?

(also everyone in this thread saying deanonymisation does not on its own solve the problem is correct)