Despite the art looking similar on the Blog, nothing screams "I'm not really a part of StackExchange" than the lack of OpenID. Why can't I use it to post instead of handing over my Name/Email every time I'd want to post?
Putting aside the technical limitations listed by Rebecca, Arqade's blog has been deprecated and is now only available in a read-only mode for historical purposes, so having Open ID support is a bit of a moot point at this stage.
For future reference, here's the link: Arqade's Community Blog.
I would very much like OpenID support on the blog. I spent a considerable amount of time researching options here. Existing plugins are either broken or actually manage to create a worse experience for the user instead of a better one.
If I (or anyone) can find a decent, working option, I will happily set it up.