Here is a small kit to start a blog and write comments.
(It is based on the default theme)
No connection or registration required to write a comment.
Missing the anti spam
Any help is appreciated!
Download: https://github.com/dsply/Small-comments-system
Screenshot:
Enjoy! 
I’m confused as to why this hasn’t gotten any love! Have you been using it in your projects? It looks great! I’ll dig deeper into this soon.
Probably because it’s not a plugin. It’s a whole system.
What’s to prevent someone from packaging it as a plug-in? Is it possible?
Only skills and time I guess. 
There are at least a couple other comments plugins, I think they are easier to install/manage:
The first comment plugin you posted was made by myself, it just a case of adding the plugin to the plugins folder and then including a comment snippet wherever you want it to appear. It also gives live Ajax notifications if new comments have been posted whilst you are on the page.
I’ve never ever used the second one you posted but it definitely looks interesting, and free 
