I'm sorry, maybe I am a special kind of stupid, but I don't think that for example the dialog you get when you click on a link is all self-explanatory. I don't even think that new users would know what features are available, for example the one-way-button in said dialog. Not only discovered I this button somewhat late, it also tricked me the first time after it seemed to do nothing at first and later, when I came back from the other thought, I just could not find the first thought. (I thought it just adds arrows to the links so you could visualise some relations with it and I don't expected it to hide thoughts if you are looking from a special direction)
I work in software testing myself and I know that developers hate writing documentation, but I think you should at least have something that explains the concepts and functionalities. Maybe today a lot of people need YouTube-Explaining-Videos like from sesame-street, but I prefer also some documetation to read an in which I am able to look things up, search and have an index. Call me old-fashioned, but TB is no CandyCrush for relaxing but an not-too-cheap-software to be used as a tool, and I like to know my tools well to put them to best use.