I'm sure they totally have access to that information, but that will tell you "X organization accessed Y at Z time", and it may be almost impossible to determin

I'm sure they totally have access to that information, but that will tell you "X organization accessed Y at Z time", and it may be almost impossible to determine what was done with that data after that point. Even if transferring the data collected was against Facebook's ToS, we at least know of one example (Cambridge Analytica) where that happened, and given that there were 8 million total developers on Facebook Graph, it's sort of unlikely to imagine there weren't thousands of other actors that did the same thing. Which all leads you to conclude, any Facebook data you had prior to 2015 is probably in the hands of someone you don't really trust. That's not a fun scenario; even if facebook fixes things from that point forward.