After spending too much time fiddling with third-party comment systems, I ended up building my own [1]. It's pretty barebones, just does what I need, and nothing more.
Each comment is written to a text file for manual review, so I don't have to worry about spam, cross-site scripting, or irrelevant comments. I usually check them on weekends and add them to my blog.
Comments are stored as plain HTML files, and my static site generator [2] builds the site along with the comment pages [3]. So in a way, it's also a static comment pages generator.
This setup doesn't meet the five attributes (no infra, rich content, real identity, etc.) in the second section of the article, so it wouldn't suit the author's needs, but it has worked quite well for me. I've been using it for at least four years (perhaps much longer, since my old PHP website did something similar), and I've been quite happy with it.
[1] https://github.com/susam/susam.net/blob/main/form.lisp
Personally I find comments not worth the bother and purposely did not include them on my site. My blog is an expression of my personality and the idea of other peoples words appearing on my pages seems weird to me.
I know people enjoy feedback, which is why I have taken to emailing bloggers whose work I enjoy instead of leaving meaningless comments.