XMPP is very much alive in large businesses, especially for system to system interop, but as far as client to server goes I don't see a compelling XMPP client - where's voice, video, chat archiving for example? Compare any XMPP client to Skype for instance and they're not even remotely close.

This requires a central server though. This is more a function of the service providing XMPP to you than the client. If you want the functionality on the client, it presumably requires some sort of interop between client and server that I'm not sure it part of the XMPP spec.

The problem is, there are far too damn many XMPP extensions and too few of them see any kind of real adoption.

XEP-0313 is a modern replacement, focusing on just the things that people actually need. It's implemented in many servers and clients already (see https://www.zash.se/mam.html ). It's still under development, but it's already in active use by many people.

This is why nobody wants to touch XMPP with a ten-foot pole.

Honestly, there's some days I wonder if there's any way to win.

Secondly regarding XEP-0136 support in OF. I did state that Openfire has only recently had 'XEP-0136 implemented across the board'.

Whilst the Open Archive plugin which provided support is a fine piece of work it was an incomplete implementation with only 1-to-1 chats (no group chat support).

I worked on merging the monitoring and open archive plugins to provide support for both MUC and 1-to-1 using XEP-0136. That work was only fully finished a couple years ago in 2013 so think my comment's still accurate.