"Interesting" was a bad choice for specificity here on my part. By the definition I mean, HN isn't interesting... It's got interesting content, but the UI is a dirt-simple server-side-generated web form.
OpenStreetMap is "interesting." Docs and Sheets are "interesting." Autodesk Fusion 360 is "interesting." Facebook is "interesting." Cloud service monitoring graph builders are "interesting." The Scratch in-browser graphical coding tool is "interesting." Sites that are pushing the edge of what the browser technology is capable of are "interesting."
None of the sites you mention above would require npm to build.
At some stage after you've seen enough 'interesting' dependencies changing the world around your app as you write it you'll realise that boring is good for most of the tech you depend on - the more boring the better, and the fewer dependencies the better.
OpenStreetMap is "interesting." Docs and Sheets are "interesting." Autodesk Fusion 360 is "interesting." Facebook is "interesting." Cloud service monitoring graph builders are "interesting." The Scratch in-browser graphical coding tool is "interesting." Sites that are pushing the edge of what the browser technology is capable of are "interesting."