[JulianMorrison]

The way you find content in Tumblr is (1) you somehow find one example of the type, perhaps from an outside link or a search, (2) you click the content and find who liked it, (3) you go to each of their blogs and if it has content you're into, you follow it. Iterate until you've connected to the entire like-minded community.

This is why I described it as a galaxy of niches. It provides a sort of discoverable obscurity that makes connecting to signal rather than noise rather easy.

It's also what makes it hard to see beyond your own niche if you don't actually own the servers.