Tumblr bans all "adult content",
to which it categorizes e.g. "female" nipples (but not "male" nipples).
Well, this is what's called being "Yahoo!d".
Get bought by Yahoo!, then wait a while and then get some most used functions broken by the new overlords because they only bought a revenue stream without understanding what it was, which then a while later declares that they are surprised and sad but the once profitable product they bought is now no longer used and therefore they abolish it.
They even did it to their own main function, when they were mainly yet another hierarchically ordered organizer. They have long ago abolished that function, even though it was the only search function they were good at.
Yahoo! would probably be better run by a board of children.