I'm no Facebook fan but the reasons behind the lawsuit are bad and could set a bad precedent. Cambridge Analytica used the Facebook API to ask users to share data about them & their friends. Stupid users agreed to that. The argument here isn't that Facebook is playing fast and loose with tracking & user data (which would be a legitimate argument), it's that Facebook is allowing people to grant access to their data to…
>The argument here isn't that Facebook is playing fast and loose with tracking & user data (which would be a legitimate argument), it's that Facebook is allowing people to grant access to their data to third-parties and Facebook should somehow be faulted for that. Even so you wrote yourself that users shared data about their friends. Why does Facebook allow people to share the data of others who didn't agree to this?
This goes a bit sideways on Facebook in two main ways, I think:
1. People are way too fast and loose with who they keep as "friends" on Facebook
2. Facebook has way too much data to warrant a blanket "Yeah, please share -all- of that at once" agreement. Something more granular, like "The phone numbers of your friends who have themselves granted permissions for their friends to share their numbers" would be more reasonable.