Basically, you've got a very exclusive view of what is a blog, and I think you've got the wrong definition of a blog. You say that your blog requires comments and wouldn't exist without them. To me, that sounds a lot more like a discussion forum than a blog.
Look at any top blog today, do they need comments. Would they disappear without them? Or, are the comments just a nice feature that people enjoy, but doesn't really change the nature of what they publish?
To me, comments are to blogs as radios are to cars. Sure, most cars have radios, but they don't need them to function. It makes the definition a whole lot more inclusive, and it should ring true to everyone. Cars of old did not have radios, blogs of old did not have comments, but as they've aged they both added new features that people enjoy (radios and comments), but to function properly, neither needs them.
If a "blog" is dependent on comments, I argue that it isn't a blog, because what is a blog but an online journal? Each of the five definitions I posted (four of which you failed to even look at or comment on) says that blogs are online diaries or journals based on experiences or hobbies. Only Wikipedia mentions comments, and only Wikipedia says "most good" blogs have them. While they may have them, there is no functional requirement that they have to be there, same with the car radio.
All cellphones have more functions than just calling a phone number and being portable. They can all store contacts in them, most have calculators, most have some personalizations you can make. Because they all have contacts, and most have calculators, do all cellphones have to have them to be considered a cellphone?
Your server part irks me. It irks me because it's wrong. You're defining the software that runs on top of the server as the server itself. Generic servers (apache, lighttpd, nginx, thin, etc) have no idea how to process a *back call. They can read POST requests, but they'll just forward that on to the software running on top of the server.
Sure, one could modify them to know how to process those requests in the specified manner, but than they wouldn't be the generic server, they'd be a specialized server.
I didn't react to the other definitions because they mean nothing. Your wordpress-Glossary has an entry for comments. The Blogger-definitions talk about how visitors may comment. Sorry, all of that points to my definition. Note that the latter interactivity-part of the wikipedia-definition is not necessarily related to "good blogs" but to all blogs.
If you want to have analogies: Disregarding comments in blogs but calling normal websites a blog is like calling a bike a car because it drives.
Server do one thing: They listen to requests on a port and forward them to a script, or serve the corresponding file. Reacting to such a request is normal business, and implementing trackbacks and pingbacks is a three-liner. They are not more of an artifical extraodinary thing than a php-script serving some output. Don't see what the classification as complex and weird here aims to.
PS: I hate it when HN eats comments!