My worry is that if Slack is replacing your documentation, then it may be that your organization did not have good (or any!) documentation that predated its use of Slack. As such, I'm not sure if that's a fair thing to criticize of Slack.
Slack is a tool for productivity. (Go on––I'll give you a minute to laugh.)
Slack does make it easier to talk to people, particularly so in a group setting. Any company can make use of that; if you are a remote company, you need that. JIRA and Trello are also mentioned as "hates", but these are also tools that make it easier to work (notably, to make it easier to organize and catalog work). If you aren't using them, you've probably written a hack that does something like them, only worse.
Slack is a tool for productivity. (Go on––I'll give you a minute to laugh.)
Slack does make it easier to talk to people, particularly so in a group setting. Any company can make use of that; if you are a remote company, you need that. JIRA and Trello are also mentioned as "hates", but these are also tools that make it easier to work (notably, to make it easier to organize and catalog work). If you aren't using them, you've probably written a hack that does something like them, only worse.