[elihu]

I think hate speech on Facebook is just the most visible problem. A more sinister use of Facebook is to use friend lists to identify people to target in real life. A bad actor might not even leave any record on Facebook itself that they're doing anything wrong.

To work off of your post office analogy, consider if it were possible for random third parties to inquire of the post office who some particular person has corresponded with in the last several years and consider how that could be abused in a dysfunctional society where being friends with the wrong person could have very bad consequences.

I don't know if there's a solution to that, other than for Facebook to be much more restrictive about who can see a user's list of friends. However, that would interfere with the way people ordinarily use Facebook.