I present the following as to why Tumblr is the superior social network (until Yahoo! starts censoring and changing it): http://twobrowngirls.co/post/69279110540/keep-calm-stay-healthy
In short, the way other networks are setup do not encourage such open dialog. Everything else is designed around social signals like Pins, Likes, and Twitter is limited by character count, so you would be hard pressed to find such an engaging discussion. No products or ads were sold during the making of this Tumblr blog conversation.
WordPress, if properly connected via JetPack could be this powerful. Here’s hoping this kind of vision is shared by those developing the core.