Messaging transports better be dumb and do the bare minimum to get the job done for end-to-end encrypting apps. Compared to #matrix homeservers #chatmail servers are two orders of magnitude more dumb, consume two orders of magnitude less resources and are blazing fast and don't require extra (central?!) identity and integration servers. With delta all intelligence, including general purpose https://webxdc.org/apps and protection against compromised networks and servers, lives on the end device.