Tumblr even discouraged linking for the reasons listed here, what with the fast-moving URL changes and the ability to keep even things that had been deleted or were posted by blogs that had deactivated. And the people who had reblogged couldn't even tell the difference unless they happened to know what became of the post/blog or the content creator individually got in touch with them to let them know, hey, I took that content/my blog down and would like it not to circulate anymore thx. Good luck with that if it had been reblogged 34,000 times. Looking back Tumblr is such a nightmare when it comes to creative control or the so-called right to be forgotten >_>