Turns out "move fast and break things" is a shitty policy when it comes to privacy concerns.
Users signed in to services they already had accounts with, and therefore trusted, knowing they were enabling features they wanted to use with their data. These services were hand selected big name companies. This is a far cry from selling data to the highest bidder for profit.
I highly doubt anyone would consent to allowing third party companies to read their private messages if that was actually made clear to them.
The average user seems to assume that the information is used to provide the service and nothing more. The last person I asked if they were worried about how much information FB has about them replied something among the lines of "Yes, but it's only things that I deliberately chose to share." (paraphrased)