The extraction of Facebook's social graph is the element I agree "finds comparison in the 2008 or 2012 races" [1]. But Obama's campaign didn't mis-represent its identity nor intentions to Facebook. Kogan and Cambridge Analytica did. Obama's campaign didn't lie about deleting its data when asked to (which, to my understanding, it wasn't). Kogan and Cambridge Analytica did. Moreover, Obama's campaign reported its backers to the FEC; Kogan and Cambridge Analytica do not.
As for Obama's campaign not being asked to delete data, all apps were required to delete data that they came into possession of under the pre-2014 policy. Those were the terms they agreed to when they deployed the app - especially one that was allowed special access to the entire US social graph (where no other app would have been). So if Kogan violated the policy, so has the Obama campaign.
Obama: "Give us a list of your Facebook friends, and we'll help you contact them about voting for Obama." While the Obama campaign did collect data about friends, this data was voluntarily given to them by users. If the Obama campaign had your Facebook data, it was because one of your friends knowingly and voluntarily gave it to the Obama campaign.
Kogan/CA: "Take a free personality quiz!" The people taking the quiz likely had no idea that they were supporting a political campaign or helping Trump win. You could have your data given to CA even if nobody in your friend graph supported it.
Also, that 190 million figure is probably inaccurate, because there is probably significant overlap in people's friends lists.
It was given to them by the 1 million users that authorized the app. Not the other 189 million (or more) users.
Also, that 190 million figure is probably inaccurate, because there is probably significant overlap in people's friends lists.
According to their own campaign manager, they "sucked out the whole of the social graph" with Facebook's blessings. So they may have actually had more than 190 million, since there are more US users that on Facebook.
"Facebook was surprised we were able to suck out the whole social graph, but they didn't stop us once they realized that was what we were doing." - Carol Davidsen, Former Obama Campaign Director