>I'm curious why FB chose to manually label the data vs collecting feedback from users.

FB is collecting data from users in a way. Yes, it is not a feedback. Since it is a learning process so getting feedback for each post is going to be an obtrusive behavior.

For more details, please refer to following line in the article - To address clickbait headlines, we previously made an update to News Feed that reduces the distribution of posts that lead people to click and then quickly come back to News Feed.