I didn't use Tumblr very much when I had an account. When I did, I used it as an author platform for myself back when I was still a fledgling writer creating YA fantasy that I was never completely happy with. I was still arrogant as hell when I wrote a couple of posts explaining, from my perspective, what made for good fiction versus bad fiction. Gods, I was so arrogant. But I later discovered that, more and more, there was an adult community growing there as well.