The question is "what type of interaction are you after?"

Chat systems are good for the "I need help now" and "I want to chat..." but for some things a single message takes an hour or day or more thought to formulate a proper response.

In those situations, the real time nature of chat causes discussions of a topic to become disjoint.

USENET, email, forums and the like can have single topic threads / chains / posts where one topic is followed across days or weeks or months which is sometimes needed for hard problems.

Slack is prohibitively expensive if you need more than 90 days of history, and Discord isn't very open or great for search.