My feeling is this is being written not just as a vent for ProcessOne adding a Matrix gateway to ejabberd but a warning to everyone thinking of setting up a trendy Matrix server or assuming enabling Matrix support will just be free. The eventual consistency model is expensive–for storage, for CPU/RAM, for client speed/sync–& everything it seems the Synapse & Dendrite servers are trying to do to speed it all up is in response of this likely fundamentally poor decision eventual consistency to ‘clone’ Slack/Telegram/Discord over allowing chat to be ephemeral & using forums for long-lived topics & Atom/RSS feeds for announcements.