Please only use JavaScript for dynamic stuff.
I'm not sure I agree that this is relevant advice today. Screen readers and other assistive technology fully support dynamic content in web pages, and have for years.
Yes, it's good for sites to provide content without JavaScript where possible. But don't make the mistake of conflating the "without JavaScript" version with the accessible version.
Readers for the blind not the only form of assistive technologies, and unnecessary JS usage where JS is not necessary makes it hard to develop new ones.
There is a huge spectrum of needs in-between, that LLMs will help fulfill. For example it can be even as simple as needing paraphrasing of each section at the top, removing triggering textual content, translating fancy English to simple English, answering voice questions about the text like "how many tablespoons of olive oil", etc.
These are all assistive technologies that would highly benefit from having static text be static.
Specifically, if you are targeting a global audience, there are entire geographic regions where the internet is much, much slower and less reliable. So not only are these people experiencing slow load times with packet drops and all that some JavaScript libraries and such might not even load. Which isn't a huge deal if your main content does not rely on JavaScript to load, but of course is if it does require JavaScript.
In addition to that, in these same regions people often access the internet through much cheaper and slower devices.
Pretty sure that ship has sailed in 2015. It’s good to see people focusing on SSR again but that’s just an extra step and it’s hard to mess up. Too many developers don’t think it’s worth it. Just try to visit any top websites without JS, even just to read them.