It's a rather slippery slope from XMPP towards software which uses any of the other networking protocols, even TCP/IP and Ethernet, since they could all be considered telecommunications.
There are options :
- they got this wrong because they don't understand how the net works
- they effectively want to control the communication by setting rules and discouraging decentralisation [https://www.rt.com/news/373706-russia-influence-europe-germa...]
- ???
That's blatantly wrong. It's the Federal Ministry of Economics and Technology (Bundesministerium für Wirtschaft und Energie). You even mentioned the Wikipedia article which states it right.
("Belongs to" is probably too strong either way. They are not part of a ministry.)
//edit: But how it is stated in the parent post is still wrong ;)
One of its tasks is to ensure non-discriminatory access to infrastructure markets for all market participants: Former state monopolies have to share their infrastructure at a reasonable price to competitors, for example. Another task is consumer protection: In february 2017 they decided that an internet-enabled child's doll containing a microphone accessible remotely without any indication to the people using that doll should be “verboten” since they classified it as a hidden wiretapping device.
The federal network agency claims that XMPP clients have to be registered according to a German law that says that one has to be registered with (but does not need permission from) the agency if providing public communication services commercially.
https://en.wikipedia.org/wiki/Federal_Network_Agency
Edit: As other hackernews have pointed out, only the telecommunications stuff is supervised by the BMVI.