To me this is a very old school, closed off way of looking at things. Who are the comments for? Just the author? If so, why make them public at all? If they are for the readers, how many readers are going to come back 24 hours later to check out the comments?

The idea that if you disagree or have a lot to say you should create your own blog post is also a bit ridiculous. Is it OK in that case to leave a comment saying "I have responded to this on my blog here at xxxxxxx"? I mean, how is the context between the original post and the followup to be maintained or even seen by the original readers?

This just seems to be more of a throwback to old school print where the interconnectedness of ideas was severely limited. Unless you were aware of and read all publications on a subject you were likely to see the entire "conversation" on a subject.

I guess if you want to see a blog article as a publication that's your prerogative, but there is a reason print media is dieing out. We should be trying to increase the interconnectedness of ideas, not stifle it.