You can be a good writer but none of that really changes the thrust of the parents point which, I think, is that: if you want easy upvotes on a site like this, you can just post some variation of "javascript bad, web 1.0 html good." If you can stretch this idea into 3 or more paragraphs, even if you say fundamentally
nothing new that hasn't already been seen 100 times, you're virtually guaranteed to get a bunch of upvotes and "DAE?" comments about how epic of an approach it is.
In this case though, the author isn't submitting it, so it's not like they're the culprit. But even if they were it's also not really an indictment of any sort either; happens to everyone who writes online; it's the siren song of "engagement" with your work. (Lots of people here want to believe this site is somehow fundamentally different from Reddit or any other forum where "internet points" dictate the flow of content. It isn't; the tics and triggers are just different. Topics like this are a good example.)
> With pure HTML and possibly some cleanly included JS he could get any visual appearance he wants
With default browser font sizing and spacing? Yeah, sure, you can get any bad look you want from pure HTML and some JS. CSS is practically mandatory for webpage readability these days, but it's all a moot point since the OP doesn't seem to be arguing against CSS in any form anyway (and even literally admits he uses it.) Honestly the linked support site is mostly OK in this regard; though I'd blow up the font size a point/point-and-a-half more, add a tiny bit more line spacing, and make the margins bigger.