True, but while they sometimes advance timelines, they keep the setting in relative stasis. I remember that Ravenloft had a timeline that directly tied into the events of I6 Ravenloft and said “A party of well armed adventurers make their way into Castle Ravenloft and are destroyed by Count Strahd.”Yes, well, how could they? The people who write the setting don't know what happens at your table, and cannot change the setting in response to the specifics of your agency - your own GM has to do that.
They could actually advance the setting based on whatever canonical ending they want to use, but will always default to the one that doesn’t really change anything. That’s why Greyhawk is being rolled back to being at war, rather than a post war setting.