Interoperability is a big part of what makes #XMPP great. However agreeing on a common strategy or even establishing a rough priority for certain features can be hard.
I believe those in-person events do a lot in getting us on the same page.
If you are an XMPP developer (client, server, gateway) I strongly encourage you to come.
I keep saying 'developer' and use that as a shorthand for: To get the most out of the summit you should have a background in reading (and maybe even writing) XEPs.