This still prompts a question, though: does this not happen on all social media? Ok, Facebook presumably dodges the problem with privacy settings. But it's no

This still prompts a question, though: does this not happen on all social media? Ok, Facebook presumably dodges the problem with privacy settings. But it's no harder to post an underage selfie on Reddit or Twitter than on Tumblr, and those sites have much larger userbases. Their apps haven't been hit by Apple, nor have they ever talked about resorting to outright adult-content bans to control it. So what's the difference? Are there any major theories other than "tumblr's site moderation tools sucked" and "tumblr's moderation team was way too small"?