If you give dangerous tools to users, you will have a few cool things and lots of tech-illiterate users screwed over.
Privacy advocates often preach solutions like the fediverse, without understanding that the fediverse is a privacy disaster for the tech illiterate. Cambridge Analytica wouldn't even be preventable on Mastodon, and it would have far worse consequences. Nevermind admins snooping on messages of their users, for i.e. romantic or financial reasons and poor people having to pay for their own services instead of seeing ads.
Yes, Facebook is horrible, but all currently known cures are worse than the disease.
I was able to download tons of user data. I think the guide was to only take what you need and you were not supposed to store it longer than 48 hours.
But that was def an honor system thing and I’d be surprised if people were purging data back then. It was (still is?) the Wild West with consumer tracking.
FB never built technical countermeasures, merely asked app devs to pinky-swear not to siphon user data.
Also facebook killed this long before the Cambridge Analytics scandal broke. It also enabled some really cool features like their graph search where you could run queries like "people in X town that like football", but it also let you run very creepy queries to stalk people, which is why it got canned.
Eventually Facebook closed all that access down and basically deprecated the concept of FB as an app platform entirely. That is a way more dramatic change than what Apple is doing to Facebook here.