There are a few reasons not to have an API on this blog. The first is such that it can only be updated when I am ssh-ed in to the server (so no one can claim I worked on my blog while working on their project). The second is because I want tight control of syndication.
Ever since Cross Origin Resource Sharing (CORS) any application should be built on its own API, but this isn't an application. This ensures true modularity and encapsulation - so it makes testing easier and builds an ecosystem around your product.