An Internet custom arose decades ago with UseNet news-groups, which are the predecessors of modern Internet discussion forums, e.g. CathInfo.  According to that custom, it's proper to reply to any question or challenge in the same topic in which it was posed.  This can lead to perfectly worthwhile topics going off-track before the on-topic discussion has been plausibly exhausted.

I can't think of a remedy that would be broadly accepted as "fair" by CathInfo members that would not require manual intervention by Matthew or Mater D.  Altho' I do have ideas about what ought to be the results of that intervention.

E.g., to remedy the "Why must the job fall to Protestants?" topic [*] that was originated by ‘hollingsworth’:
•   Create a new topic in his ‘Computers and Technology’ (sub)forum about searching for the misnamed "A i kins", e.g., by moving current Reply #15 by ‘Alligator Dicax’ to become its original posting;
•   insert a visible-&-clickable URL link from the Reply #9 by ‘hollingsworth’ to the new ‘C.&T.’ topic to which the off-track replies will be removed;
•   for logical continuity, insert a visible-&-clickable URL backlink from original posting of the new ‘C.&T.’ topic to Reply #9 by ‘hollingsworth’;
•   devise 2 distinctive rectangle-enclosed messages to be placed, eventually automatically, with more formal language expressing their significance(s):
   •   Text was yanked from here to a new topic by an admin, to keep this existing topic on track;
   •   Text yanked from an existing topic elsewhere was moved to here by an admin, to keep that existing topic (elsewhere) on track.
•   Oh!  Feel free to delete the troll-like Replies #16 and #19.

I believe that Matthew has already written a tool (PHP? PERL?) to simply his effort when stripping out postings that are unacceptable on CathInfo.  Enhancing its capabilities as indicated by the example above doesn't seem as if it would violate any assumptions that simplified coding his existing tool, but only he would know for certain.

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Note *: <https://www.cathinfo.com/general-discussion/why-must-the-job-fall-to-protestants/>.  It arguably went off-track in Reply #15: <https://www.cathinfo.com/general-discussion/why-must-the-job-fall-to-protestants/msg648302/#msg648302> (yes, moi), and certainly by Reply #17 (but see "Internet custom",  above).