One might ask what could possibly be a reason behind a blog with no comment functionality or a blog that turns comments off. Blog authors site being fed up with weeding out spam or offensive posts, or spending too much time answering comments.
Everyone certainly has the right to use whatever model is more to their liking. If your concentration and focus are mainly on getting your information out there and not wishing to engage in discussion about your posts then by all means, leave your comments off.
One clever option for those who chose to turn comments off is allowing readers to visit their Technorati blog reaction page. People can comment on their own blog and then link to the original blog to continue the conversation. Ahhh...would your consider this Technorati authority baiting? The more blog reactions your blog pulls in the higher your Technorati authority - end result high popularity in the land of the "green giant".
One of my favorite blogs the Official Google blog has never had comment functionality....but then that's GOOGLE.
In part by definition, a blog (according to the omnipotent Wikipedia)
Blogs provide commentary or news on a particular subject such as food, politics, or local news; some function as more personal online diaries. A typical blog combines text, images, and links to other blogs, web pages, and other media related to its topic. The ability for readers to leave comments in an interactive format is an important part of many blogs. Most blogs are primarily textual, although some focus on art (artlog), photographs (photoblog), sketchblog, videos (vlog), music (MP3 blog), audio (podcasting) or sexual topics (Adult blog), and are part of a wider network of social media.Choose what works best for you and if you happen to run across a blog that doesn't allow comments and you're just dying to "comment" about what you've read - head back over to your blog and post about it linking back to the original blog that was the catalyst for what I'm sure would be a magnificent read.

