What I take away from this is the idea of each post having its own identity and feel (each post with its own unique stylesheet). Contrast to a blogging platform like Wordpress or a SSG like Jekyll where every post is generally formatted and styled exactly the same way. The author's blog posts are now these unique time capsules.

Obviously a blog at scale isn't going to do this, but I do think there's value in what the author is trying- where each post is styled and formatted independently with care instead of unceremoniously dumped in with a one-size-fits-all stylesheet.