I understand there are tradeoffs and an initial design (narrow) scope. However, the guest said it eloquently himself that as hardware and software improve we can dream of better things than what as initially planned. I disagree with you that we don't need to be anonymous/private in public large group chats. You choose to use the same nym in all of them and that is your decision. But others might not feel comfortable being in 2 conflicting groups knowing that 1 of the participants might cross check the social graph and find out a bunch of groups you are on as well.