This reflects my experience. The people I work with now use slack exclusively for work and the odd share of more personal items while on vacation/weekend/walk during lunch. We have similar interests so the content is always welcomed. Any important discussion happens offline or on the phone, though. I can’t imagine us using slack for anything outside of trivial, asynchronous messages and events reported by bots.
At most other companies I’ve had people message me about salary concerns, unionization, anger towards a manager or CEO, endless banter about anything but work, etc. The main difference was that these places were run by people who really didn’t care about their employees and slack ended up a reflection of that. A lot of upset, frustrated, resentful venting in private channels.
If slack didn’t exist, these conversations would have happened some other way. There’s no way everyone could keep sane in a bad work environment without some degree of venting or comradeship.