A very interesting analysis. I used to be a pretty avid user of Tumblr, but I stopped because 1. People I knew in real life were using it as a soapbox for personal issues and there was all sorts of drama there, and 2. As you mentioned, there was a very, very virulent strain of group-think. I think that second issue is actually becoming a big problem all over the Internet, in a sense. It seems to me that not only are people very willing to fall in line with a certain view (and, bear in mind, I'm a lefty that definitely agreed with a lot 'mainstream' Tumblr thinking, sure) without necessarily critically thinking about it, but also people are very keen on absolutely demolishing others' views in a pretty ad-hominem manner. It's pretty worrying to me actually. I think Hubski is probably one of the better places that I've found where you can have a discussion with someone who has a differing view without it turning into flinging shit at each other, but there's still some of that same condescension to be seen.