[dmitriid]

> Support for multi-device sync is part of the suite of protocol features required by modern XMPP implementations, these requirements are updated every year

The problems is that many of these modern features were unbelievably late.

I still remember "The State of Mobile XMPP in 2016", https://gultsch.de/xmpp_2016.html

At the time, 9 years after iPhone had come on the scene, most modern features were still experimental draft proposals implemented by no one.

5 more years later there's maybe one client that implements the modern features (Conversations for Android IIRC), and that's about it.

And it's an unknown how many servers implement those features.

[seba_dos1]

> 5 more years later there's maybe one client that implements the modern features (Conversations for Android IIRC), and that's about it.

...and yet I'm using three different modern clients that work well with each other.

> And it's an unknown how many servers implement those features.

Enough to make me not have to care about it.

[MattJ100]

> And it's an unknown how many servers implement those features

It's not: https://compliance.conversations.im/tests/

Obviously a new user is not expected to fathom what all this means before getting started, which is why there are curated lists of public XMPP services, e.g. https://providers.xmpp.net/ and https://joinjabber.org/ and for private servers there are projects like Snikket where the server software is developed in parallel with apps to ensure a consistent feature set.