Explain me how this is better than IRC.

Lots of reasons. For example, you can't just paste a picture from your Clipboard into a IRC channel and expect it to work. Granted there are image hosting services out there, but if you want a chat server on your private network and you are a small company, you want it all in one. Same goes with highlighting mentions, Desktop notifications, saved transcriptions (IRC is transient by nature), LDAP/Kerberose integration, XMPP support (again, there are XMPP bridges for IRC, but not integrated in any free private IRC server I know of). UI is another aspect too.

IRC is a bit less accessible for non-technical people. We had a lot of trouble getting our team to adopt it. It's not for everyone.

That's why products like Slack, HipChat, Campfire, etc exist.

I don't want to dismiss your efforts, but in the spirit of the original question I'd like to know: Is it only a UI problem, or is there a problem with IRC (the protocol) itself ?

The lack of persistence built into the protocol (and thus clients) is a big problem for team communications. You can have a bot log your channel, but they'll often have holes creep into the logs somehow, and for private discussions require yet one more access control system.

Having a web irc client that provided a common backlog and search for all users, instead of requiring things like znc to make that usable, would be great. The private part is fraught though.

/query?

/query command is news to me, but appears to be completely unrelated (I don't really understand the naming).

It was definitely a UI problem for us. I don't think the underlying protocol matters much, we could have used IRC.

Why does every attempt to improve user experience these days, make the assumption that they need to rebuild the entire stack from scratch?

A really high quality web (maybe even HTML5 client-side only even?) XMPP client would be a welcome thing. This, not so much.

This wasn't exactly "an attempt to improve user experience". It's a hack day project that we use internally to help the different BU's communicate. The bonus is we get to have fun with it because we wrote it.

lacks offline mobile support :-(

This is something can consider for a future release. Do you mean offline message storage, so you can look at discussions offline?

I want to see some (or a lot of?) chat history offline, and then send msgs while offline. I don't want it to scan the network, delay loads, or blow up in any way just because the network is down. Think about the Whatsapp or Telegram experience, as opposed to Slack or Facebook Messenger. If you are in and out of the subway, or in elevators, or just where there are spotty networks, the mobile experience blows for anything but the super popular and consumery chat services.

Unlike the people who can't figure out why this is better than IRC, I find a ton of value in your project. After leaving Campfire, moving to Kato, and then settling with Slack, I am really unhappy with the Slack mobile experience.

Thank you for getting back to me. I'll open a feature request for this and see if we can fit it into a future release.