Update:
When looking through the comments in meta, a common theme emerges that when forums grow to too many categories and subcategories, users begin complaining that the forum is overwhelming and no longer intuitive. This is the issue we’ve been struggling with since moving multiple teams and projects over from Trello and Slack.
Like in this thread: Customizable Homepage or Discussion Feed?
Using a navigation system built around tags either within the category structure, or ignoring it completely, would transform this.