What so it just styles your site to look like a dry academic paper? What use case does this have? I imagine someone out there really needs this and the target audience is small.
I see out-of-the-box latex looks mostly in shorter student reports - although even there, you often get more modern looking styles.
https://thomaspark.co/2015/01/pubcss-formatting-academic-pub...
https://thomaspark.co/projects/pubcss/demo/acm-sig-sample-we...
When I read something written in the style of a medium post I sub-consciously think of the material as being shallow. While reading this type of LaTeX style I would start taking it more seriously. But the texts with most serious look to me are non-formatted pages, like the ones on danluu.com or even plain text posts like this one: http://fmwww.bc.edu/RePEc/bocode/t/transint.html
By the way, this is also why I used serious words like "brain" and "assess" and avoided typos: to make my comment look trustworthy. I had to put a front warning in terms of "wet finger" to lower that a bit though. The Hacker News style and context already make it feel far too scientific already.
For texts like in your link, I automatically expect they are written in the 90s by some very clever person and when I find some that are from the 2000s or later, I think "wow, this is actually new!".
What would be your impression with such a text written in Comic Sans? I would probably be completely lost I think.
just take your L and move on.
Success of CSS themes depends a bit on fashion, so there's some risk that a popular theme will implode by getting too popular and then feel bland, overused. Or shifts in preferred styles making the theme look dated.
The LaTeX approach is sort of an anti-style. It's a uniform. I'd bet that this CSS theme will send the same message (I am an academic, and this content is for academics) for many years. A uniform should actually gain popularity as its used. Although you are correct that the reach of this theme may be limited to just academics who create websites.