Your comment actually deserves a better response than I gave it. Spam is the open protocol killer. It's a totally serious issue. If our goal was to replicate HN or Reddit via only personal servers, I would be pretty dang paranoid about getting our anti-spam solution perfect:/

Happy in the case of Facebook-on-personal-servers, we have all the advantages and the spammers have all the disadvantages. Social network's main purpose is communication between people who know each other. Ignoring the Pages part of FB (which is really more Reddit-like than it is essential to a social network) communication happens between friends, or friends of friends commenting on photos or whatever. Spammy friend requests will be a problem, but that's not too big of a deal.

And then, once that's done . . . ahhhh. Your own filtering software, blocking game notifications to your heart's content (since it's your own server you can install whatever filter you want, though of course there will be good defaults). Guess where most of the unwanted posts on Twitter or Snapchat come from for me . . . Twitter and Snapchat. No more!