> You can create as many Slack channels as you want, but all that is worthless if you don’t build the culture where it’s okay to use them.

Well the problem with corporate offtopic spaces is obvious: It is (potential) surveillance. One of the essential properties of the coffee kitchen at the office is that only you and the person who was there know what you said.

People at work will occasionally like to talk about things their collegues or bosses don't need to hear. That doesn't even mean it needs to be badmouthing others. Let's say you're really into model trains, it is easier saying that in person to the one other guy who acts a bit nerdy, than to announce it online in front of potentially everybody.

I leave it to you how you think this could be fixed.