If you don't want to allow comments in a blog then you can very easily turn them off.
Go to the Access and membership settings category in the blog and clear the Blog comments checkbox in the Access to sections part of the form.
You can also change this by going to the Resource permissions settings category, selecting Blog comment and then clearing all the View checkboxes. You can also there choose if you only want members with particular roles to be able to comment.
Making a blog only for posts.