@greatsword My personal understanding: Delta Chat simply started as a "chat over email" app with basically none of that custom stuff. Even PGP wasn't there initially: https://delta.chat/en/2017-06-01-delta-chat-0-9-0-released
Only later (past ~1 year) focus has shifted somewhat, and "chat over email" has been removed from app store descriptions.
For more discussions, see https://support.delta.chat/t/why-choose-delta-chat-over-xmpp/3549?u=wofwca

