[arendtio]

Well, it doesn't fill anything but was there before XYZ came. Matrix has mostly the same properties (open source, federated). Signal is not federated and WhatApps is neither federated nor open source (but has the most users).

The things that make XMPP unique are very superficial. For a long time, it was the dominant IETF Standard for instant messaging and it has proven that it can adapt to new circumstances (mobile clients), but who cares about such stuff nowadays ;-)

Compared to running your own email server, you just have to solve different problems:

- XMPP has higher uptime requirements (from a user perspective)

- spam is not such a big problem for small installations

[mananaysiempre]

Compared to Matrix,

- Much lighter in processing and storage requirements (at the cost of group conversation history being a crapshoot)

- Not de facto controlled by New Vector, which I’m gradually losing faith in[1][2]

[1] https://news.ycombinator.com/item?id=38162275

[2] https://news.ycombinator.com/item?id=38451920