Blog Commenting: Enable or Disable?

The Romney Five and Cate Edwards accept comments on their blog posts after some moderation, but Meghan Mccain and her buddies don't take any feedback at all. When you don't enable comments, doesn't a blog by definition morph into a column or a diary? Call it something else, I think, because the communal blogginess of a blog is sucked out when people can't respond to a post. (Fine for me to get all huffy about it 'cause I hardly get any comments at all ... sigh.)