There are situations where different people use the same machine to access Facebook. And indeed, where they also (foolishly, I know) expect that Facebook will p

There are situations where different people use the same machine to access Facebook. And indeed, where they also (foolishly, I know) expect that Facebook will preserve mutual privacy. Partners. Parents and children. Siblings. So Facebook, if it's relying on hardware/software fingerprinting, might compromise multiple users to each other.