I don't think you're thinking about this. e-commerce is more than just a document and SEO is massively important there but javascript makes the user experience miles better; Think product variation selectors, bulk pricing selectors, product filtering, realtime cart, etc, etc. It's insane to say we shouldn't use new tech so that the search engines can index us, do we just forever stick with what we had 15 years ago and never progress? Madness.
The Web technology folks still circle around the same problems like 10 years ago when the actually popular and successful websites like HN and others deliver superb UX with the dinosaur tech.
Anything that is actually using the advanced Web technologies are not in the domain of SEO, stuff like true web apps like Figma, Google Docs let's say. At best, you can index list of content for those but that list could have been a JS-free HTML rendered by PHP.
Now that I'm at the receiving end of the Web based products, i assure you the experience is horrific. I don't even use search engines as much since the AI went mainstream and can't be happier.
Good riddance.
Of course I do enjoy things made with the advanced Web technologies like Wasm, Figma for example. I'm every now and then impressed by some web app that does something I thought not possible before.
However I'm still disgusted by documents that are some images and text loading tons of stuff that don't do anything beyond degrading my experience by slowing down the response time or act weird when interacting.
That's not the subject of Show HN's, though, which is a great reason not to post generic fighting comments in people's Show HN's.