Purple cow was an apt metaphor for the first wave of blogging. Many of the first bloggers were purple cows.
Now that there are so many blogs, purple cow isn't so helpful. After all, we can't all be purple cows - not unless purple is the new brown.
Yes, every blog and blogger is unique in the same meaningless way that every person is unique.
What does it mean then? For me, the blog is not meant to help me do or achieve anything, rather the blog helps me to exist/be in this other place, the blogosphere. Could it be that one day, we all might be expected to exist in this way to fully participate in life? It's impossible to know the answer. All I know is that I like this form and that's good enough for now.