This makes perfect sense, since as a user-generated content community, a large portion (not a majority, but a large part) is in very shady shit. /r/jailbait, /r/thefappening, etc.. But for everything shut down, there are countless others that are still operating, like /r/FacebookCleavage, /r/photoplunder, /r/redpill, /r/greatapes, etc..

Reddit has expressed that it wants to be totally neutral so that it can model a "new type of online meta-community" that has literally no curation for types of communities. They want to have /r/MensRights'ers and /r/feminisms'ers on the same site, fighting with each other, generating ad impressions. They want to attract white supremacists and misogynists and feminists and people of color alike.

So, the main thing they need to guard against is conflict on reddit spilling over into the real world, and the best way to do that is to strictly prohibit posting personal information.

Of course, "personal information" doesn't extend to things like naked photos taken and distributed without the consent of those depicted, but you can't use that to make Reddit a scary place for misogynists. So it's okay.