I think maybe what is being referenced here is the feature on the main Sutta Central site that links to any discussions had about the sutta on the Discourse pages:
As an aside, I did just do a test with this post and the sutta it references and nothing seems to show under Discuss & Discover so I wonder if something got a little broken, or if I’ve just missed how discussions and suttas are linked up.
As for the mail point, though, while I share in reservations expressed elsewhere in these pages about the usefulness of tags in many cases, here it might be a useful way to bind the collection together without things getting too bloated, as exemplified by Bhante Sujato’s ebt series.