The actual coherent arguments are a) people didnt know what information they were sharing b) didnt understand how that data could be aggregated c) what the share data with a vendor button did d) should be trusted to wield this kind of power e) that entities should have been able to aggregate data like that without arousing suspicion. f) who is even responsible for this error in judgement (data sharers or friends, or facebook or ca)
The data leak here was people pressing "give away my friends data." Facebook designed the system that allowed it, hosted the data collector, incentivizing the bad actors to build their collection quizs and was responsible for communication of how the permissions system worked, but the data leaking itself was the sum of millions of people being careless with what their friends data. Facebook itself didnt directly leak the data. This was an aggregate human misbehavior.
It'd be great. But at the same time, interoperability brought us Cambridge Analytica scandal. I don't know who social networks could be interoperable without data leaks.