I assume they thought they'd be teaching people a lesson by making them feel foolish for responding to AI stories, most of which were too fake to be believable.
However it did not matter. The posts remained popular and continued to bring in comments even after the admission that they were fake. In advice subreddits, commenters continue to give advice on the situation. Some comments would say they saw the notice that it was fake but continue arguing about it anyway.
This makes a feature of Reddit very clear: The truthiness of a post doesn't matter. The active commenter base on popular subreddits just wants something to discuss and, usually, be angry about.
In retrospect it's obvious given that misinfo posts were the easiest way to karma farm for years even before AI.