The Washington Post makes clear – Facebook has made its internal data available to nearly any software developer, somewhat clamping down in 2015. They even leak – intentionally – data about your friends, such that even if you consented to leak data, your friends probably didn’t – but Facebook did not care and still does not care.

In 2011, Carol Davidsen, director of data integration and media analytics for Obama for America, built a database of every American voter using the same Facebook developer tool used by Cambridge, known as the social graph API. Any time people used Facebook’s log-in button to sign on to the campaign’s website, the Obama data scientists were able to access their profile as well as their friends’ information. That allowed them to chart the closeness of people’s relationships and make estimates about which people would be most likely to influence other people in their network to vote.
“We ingested the entire U.S. social graph,” Davidsen said in an interview. “We would ask permission to basically scrape your profile, and also scrape your friends, basically anything that was available to scrape. We scraped it all.”

Source: Facebook’s rules for accessing user data lured more than just Cambridge Analytica – The Washington Post
I have reduced Facebook’ apps from about 48 down to 12, of which 8 are my own for my own blogs, one is for Instagram which is already part of Facebook, and 3 others are for 3 specific web services.
I have gone through and deleted a number of “Likes”. Likes accumulate surprisingly rapidly when we visit Facebook – in a matter of minutes we may like half a dozen or a dozen posts, giving valuable information to Facebook’s database and customers.
Facebook does not make it easy to delete or change old data. Rather than provide a bulk delete or unlike feature, for example, Facebook requires you to page through every Like, Share and Comment you have ever made – then select a drop down menu, then select Delete, and then click Ok to confirm the delete – for every single item.
Facebook does not want you to delete anything – ever and makes it very difficult to go back and delete old posts. Is Facebook serving the customer needs? Yes, when you realize you are the product and not their customer. Mark Zuckerburg does not give a damn about you!
As of this week, I am no longer clicking Like on any posts, especially any marked “Public”.
A LOT of people right now are starting to reject Facebook, even hating Facebook. Facebook is not “your friend” in the least; Facebook is more akin to a nightmare operation, or perhaps the Dr Evil character that inhabits James Bond films.
Update: Amusingly, this Washington Post article bemoaning Facebook’s invasive snooping, provides Facebook login as an option to post comments. Which of course, enables Facebook to deposit cookies on your computer and track your online – but off Facebook – behavior too.