Telegram is giving away FREE Premium subscriptions! All they need from you is to use your cell phone as a relay to text out their OTP codes! And the recipient of the OTP sees your phone number! What could POSSIBLY go wrong with this deal?
PLEASE don’t use Telegram! I personally recommend Matrix as it’s totally FOSS, you can self host, there are tons of front end clients to choose from. Or even use Signal. I have my own issues with Signal, the fact they don’t allow third party clients, you can’t self-host, they have a proprietary shim in their stack that only they know what it does, they were pushing crypto, etc, but at least Signal is better than this garbage.
Prosody is also a great server with a ton of functionality.
For the tech crowd I think Signal was just very enticing as it was easy to convert non techies with smart phones. That’s the discovery arguement, but I find that point moot since a properly configured setup should allow one to use the same address as ones email address for XMPP (much like gtalk). Now signal claimed to have social graph anonimity, but for the longest time that was not true at all for a state sponsored adversary (it has technically improved but I’m not 100% sure that is true in practice).
There is a XEP for server side history, it’s been around since 2012: https://xmpp.org/extensions/xep-0313.html