Is there any point in not supporting some of XEPs? Could you give me examples, please?

Thank you! But I'm not sure about moving to Matrix, since all of my contacts use XMPP. Also I believe I can communicate with Matrix users via bridge, if I'm correct?

Good points! Thank you :)

What kind of meta-data could it be?

I'm hosting syncthing on my server to sync obsidian notes between my pc and phone, even when one of the devices is offline. I find it very useful. Also, nextcloud, jellyfin, qbittorrent, monero node and netdata for monitoring my server