I've worked at companies where we had great communication policies around slack. Slack rooms were for the room topic, not for conversations.

There was an off topic room where people could be social and shit talk.

But basically due to our moderation rules, we really encourage people to keep channels on topic. Which made it more useful, less noisy. So it's a social network and so far is social people use it. But the structure on top of it is determined by the company policy and the culture