Getting expired tmblr accounts indexed through Google Webmaster

The main sub domain url ( (mysite.tumblr.com) will index fairly easily. But I did have few take a few months. The individual posts will very rarely index. The only way I have been able to get Tumblr posts to index is to create backlinks to the post (mysite.tumblr.com/post/123577). I have seen the same with expired Weebly also. The main sub domain will index but posts will sit there forever unindexed until link to the post get indexed. Even nofollow links helped index.

I would assume Google places little value on individual Tumblr posts, may because the platform is more of a social media platform than a blogging platform. But if the post gets links then it becomes important enough and indexes the url. Just a theory of mine.