My main problem with many (most?) chat tools is that of retrieving information. In Element (the default Matrix client), search isn't (yet?) implemented. So how do I find the note from some days ago where I remembered a keyword? No search ... ok, let's export the chat protocol then (onto an encrypted disc, because security) and search with grep or even agrep, but ... no export option either. So the bottom line is: information lost in cyber space.

This never happened to me with email, even when encrypted (as long as I have the privates keys). All MUAs offer search capabilities, and/or exports so I have access to existing information.