Tumblr’s current guidelines for so-called “sensitive content” conceal, though not very well, one minor detail:
If a significant portion of your posts are sensitive, and especially if they are sexually explicit in nature, then we’d appreciate you marking your blog as “Explicit,” which will keep it out of search results for people in Safe Mode, and prevent any logged-out users from seeing it on the web. You can do this in your blog settings.
That’s just the lead-in. Here’s where the boom is lowered:
I marked my blog as explicit. What happens now?
Now you can be sure that only suitable audiences are seeing your content. Blogs that are marked explicit are kept out of search results for people in Safe Mode. Anyone viewing your blog on the web will have to be logged in (with safe mode off) to see it.
Which means, of course, that individuals who are not already part of the Tumblr “community” will not be allowed on the premises at all.
This strikes me as awfully blue-nosed for a service which at one time had over a hundred thousand blogs with the words “Fuck Yeah!” in their titles.