Because with a blog I have time to think and edit and have full control of the page if I ever change my position which, without the whole picture, I sometimes do. Where as if I post a reply it is often a gut reaction that later I sometimes regret making. I often grimace at some of my older comments on here and other sites which I cant alter or remove.

I also wrote a post recently on why it is sometimes dangerous to make these type of un-thought out comments that people can trace back to the real you, I think that part scares me more than anything https://rodyne.com/?p=2154