Great question -- chat is a great interface for anything that falls out of the "easy to fully automate" category. As an example, we use continuous deployment internally; but there are times where we might want to deploy a branch to a branch lab for experimentation. If that happens, doing it from chat lets everyone else know that it's out there (and how to do that deployment).
Chat is also a great environment for getting notifications about extraordinary events. We get notifications in chat if a link on our homepage is 404ing, whenever deploys happen, or as scheduled updates for things we want to pay attention to but don't want to manage a separate website to handle them.
We usually start with small commands and then grow them to automate more of the "well trodden path" as we understand what we want to automate. Because every command (we call them skills) can expose an API, it's possible for an Abbot skill to respond without any person being involved.
That is, when is chat-initiated typically a better fit than something initiated by a check-in, build, incident detection, and so on?
(Not knocking it, just curious)