Why? Please explain for those of us like me who don't understand.

When something is posted that was not published in $CURRENT_YEAR, it is convention to add the year of publication, in parenthesis, after the title.

(Some leeway is provided during the first few months of $CURRENT_YEAR.)

this article is a 5 year old argument in bsd dev community, it's impossible to know if it's relevant from an outside perspective