This process could be faster for sure, but that requires independent developers to work on implementations and to share their experience.
Because if have to look through tables and bug trackers to figure out what client/server combination I can use (and have to pester my friends to use(!)) you can't count something as "addressed" IMHO. I still use only a very basic set of features with XMPP, because in my experience attempts to get anything advanced are way to time-intensive to be worth it for the few buddies still on XMPP, and I can't really push new people onto it that way.
Let me stress this:
> production systems are advised to carefully consider whether it is appropriate to deploy implementations of this protocol before it advances to a status of Draft
That's from XEP-0363: HTTP File Upload.
Not sure this works as well elsewhere (e.g. the Matrix spec just states that it's "still evolving: the APIs are not yet frozen and this document is in places a work in progress or stale").
> WARNING: This Standards-Track document is Experimental. Publication as an XMPP Extension Protocol does not imply approval of this proposal by the XMPP Standards Foundation. Implementation of the protocol described herein is encouraged in exploratory implementations, but production systems are advised to carefully consider whether it is appropriate to deploy implementations of this protocol before it advances to a status of Draft.
It means that there will be one client that supports this (Conversations for Android) and maybe one server supporting this (probably ejabberd). Good luck navigating the minefield :)
Meanwhile I can install Slack on multiple devices and have the same functionality everywhere :)