By establishing a long history of antagonism, which helps explain one-another's attitudes towards each other, and why the Klingons were so eager to invade Cardassia.
Not according to Garak. He seemed to think the incident was unimportant, no matter how long it lasted.
Which is why I did not speculate as to the writer's intent.
Saying it was "something they meant to get back to but never did" is not speculating about the writer's intent?
I think the line was a throwaway one. You don't. Fine. Argument over.