You're spot on, however the pervasiveness of this kind of data collection and analysis seems to have really picked up in recent years.
In my workplace a similar tool was put in place to keep an eye out for potential fraud, sensitive data being shared, that kind of thing, but at least one exec very quickly started asking questions about "enhancing" it, laughingly suggesting it could help identify flight risks in areas they're looking to cut headcount in, so they could "remove barriers to their exit" rather than having to pay severance. (To quote the great philosopher Nelly, "I'm just kidding like Jason... unless you're gonna do it")
Don't forget too that this is just monitoring chats, there are plenty of other sources of data that could be used against you if so desired.
IMHO the issue isn't so much that people are using work-controlled platforms to say things that workplace doesn't like (though that is an issue), it's more the shift in the employer mindset that tools like this enable, and the huge imbalance it can create when it comes to salary negotiations, constructive dismissal, mass layoffs, union busting, etc.