That makes me think... what kind of insight into facebook's inner workings might we get from the discovery?

ah yes, another "bug" that happens to result in massive data collection, oops.

This thing where Facebook collects a lot of data in ways to which most people would object for years and years, and then when they get caught they claim it was a "bug", is getting really old.

To make matters worse, they usually tend to re-introduce the "bug" as some kind of feature a few years later, as their way of saying "yes, we really do thing our users are that stupid to not realize what we've done, why do you ask?!"