Actually triggers a good, 8-9 year old memory. Two places I worked at used to communicate through HipChat. It was simple, native, and did the job until Atlassian fucked it up with a massive rewrite. But even then it was still decent.
In both cases there was a massive bike shedding moment where the company engaged in a chat-war, with one half being solely devoted to Slack, and the rest of us holding back and saying why we need to switch. In both cases the Slack advocates went rogue and since they were also the loudest voices, people switched over just to get back into the conversation.
I have no idea what spell was cast on those people by Slack but, god damnit, it worked. It's just IRC in a walled garden and costing 10x as much, with shitty features you can't opt out of (like the new editor and threads, which birthed a whole cadre of slack micro-managers).