Sure - you probably know better ! Let me step back and explain what I am saying ..

At this moment of this conversation - you don't know who I am , I don't know who you are .. this is an anonymous conversation . This conversation is open to everyone . Suppose there is a third person who knows me as well as you - s/he can verify this conversation is between two of us - because contents are public and digitally signed by us. That is what I mean by "anonymous and public" . The word pseudonymous was coined much later .. we can go deeper in that if you like .. but that is unnecessary :-)

Sure you can find out who I am if you start a quest - like checking the meta-data or employing NSA :-) .. there is NOTHING that is absolutely hidden provided proportional efforts / interest.

If I get into a private simplex chat with you , there is no way for a third party to confirm that the discussion is between you and me. Which means you need to have a foolproof mechanism to know who I am . Which means we are not anonymous to each other. Thus a private conversation can't be anonymous . Sure two anonymous people can have a random chat - like two persons talking in a traffic jam .. or in a public garden .. that conversation is just exchange of pleasantries .. or letting each other know Sun is pretty nice and warm this morning :-) Just to rehash the point - there is no good reason for two of us to chat on Simplex :-) .. but the anonymous public chat is quite useful - to third parties who know where we are coming from ... even to random people who have no clue of our true Identities.