Due to much confusion, consternation and general concern, I offer the following three step process outlining how to leave a comment on blogger:
1) Click at the bottom of the entry at "0 Comments" or "1 Comment" or however many comments it says.
2) Go to the bottom of the comments already there and click, "Post Comment."
3) Ignore the exhortation to sign up for Blogger and just post anonymously, unless you want to have a blogger identity, in which case go for it.
4) Leave a comment. Bask in the warm glow of bloggerdom.