The definition of "telecommunication services is in §3 Nr. 24:

https://www.gesetze-im-internet.de/tkg_2004/__3.html

Translated "consist wholly or predominantly in the transmission of signals over telecommunications networks, including transmission services in broadcasting networks". I find it hard to argue that some piece of software can be a transmission service.

From the other hand, GMail was considered a "telecommunication service" by a German court:

https://www.noerr.com/de/newsroom/News/gmail-ist-ein-telekom...

Translated: https://translate.google.de/translate?hl=de&sl=de&tl=en&u=ht...

However there is an important difference:

"Google Inc. therefore has its own switching technology (original "Vermittlungstechnik" - transmission tech) and therefore has, in any case, partial control over the signal transmission."

An XMPP-client, in contrast does not have own transmission tech and has no control over signal transmission.

> IFF the relationship between the states and the governed was healthy you wouldn't bat an eyelash at the suggestion.

Please clarify what suggestion you mean: that XMPP clients are telecommunication services or that their developers need to register?

The client is a component of a communication service. Such components used to be (mainly devices and) developed solely by corporations already integrated into the 'system'.

You don't trust the system, and you have good reasons for that, and the 'system' doesn't trust actors it does not control.

It is that simple.

I just asked for a clarification of what suggestion you exactly meant in your original comment and I still have no idea after this response.