[Shoothe]

> They too though made a Google-like transition and went from an open protocol (IRC/XMPP) to a closed/custom API. At least here, the server admin can enable those protocols if they want and the API seems to offer enough features that someone could probably integrate Slack into another IRC-like client.

As for the XMPP gateway it's just barely usable. From my personal experience it even tended to drop messages from time to time. It seems Slack added it just to claim XMPP compatibility. Just look at where is Slack placed in this ranking https://conversations.im/compliance/