This is actually the most relevant argument. I don't think any self respecting Tumblr user would contend that they speak in a vaccuum. The dashboard is central

This is actually the most relevant argument. I don't think any self respecting Tumblr user would contend that they speak in a vaccuum. The dashboard is central to the UI, and it's for this reason that they probably have yet to release a full API or even an RSS publicly.