Ask HN: What's up with web based blog readers?

What's up with the lack of many web based blog readers?

Currently there are Google reader and Bloglines (I am using it) and Wikipedia says Rojo is still around. That's it. Why?

Is the reason for this because Google Reader just works, can scale, is fast and is free?

Marshall Kirkpatrick thinks this is awful (http://www.readwriteweb.com/archives/bloglines_is_back.php).So do I. You?