If I read that visualization correctly, their homepage traffic increased +1000% while the pageviews on specific areas like tech / politics didn't increase at all over the same time span. That's not something I'd be happy about.
When was the last time you clicked on a category tab on any site?
I can't recall every doing it. I think psychologically we assign very specific use cases to our media. Go here for X. Go there for Y. Go there for Z.
If you go looking for X, it's either there or it's not. You're not going to click on a tab to try and see if that subsection has what you're looking for. You're going to hop to another site that's focused just on doing X.
That's a good point. It probably means that people go to cnn.com to know what's going on, but don't see CNN as the best place to get in-depth or specialized content.
That's Tumblr's equivalent of commenting. I find that it's much more minimal than normal comments, while still letting people respond to the author.
It's not as good, mind you, as showing no response to your work at all and letting it exist in and of itself, but people still use blogs as conversation, and I think reblogging's a much subtler approach to the problem.
The problem with this approach is that each person has their own picture. On a very popular page, this has the tendency to make the page very slow as it loads another 100+ items on the page yet adding nothing to your experience.