We all know (although, as an American, I hesitate to speak for my
British colleagues) that the thread is way off topic, and has
undoubtedly gone on too long.

This particular and seemingly superfluous use of the comma in
enumerations before the final conjunction, sometimes encountered
when reading English, has always struck me as both odd and interesting,
as it seems to introduce a pause or hesitation before concluding the
list of items, thus lending particular emphasis to the last one.

(Much worse, in my opinion, the - maybe transatlantic - habit of putting
the endquote after the period, "like this." Completely illogical :-)