If it's just your hobby site... great, develop it without JS.
But if it's a site people pay to access (or requires ads) and they expect some functionality - like Youtube or Netflix say - I don't think this is possible.
As far as I understand it, YouTube and Netflix are a nicer UX with JS but there’s no particular feature that would kill it completely.
Like, for example, I thought that you can play HLS* manifests from plain HTML5 video tags.
EDIT: I was thinking of HLS and not DASH
But HLS has wide support on mobile browsers, and on desktop Safari. (Source: https://caniuse.com/http-live-streaming.) So YouTube should in theory be able to support JavaScript-free playback for many of its users.
Do you think that difference would materially affect whether YouTube or Netflix could exist as a website in a meaningful way without JavaScript?
By meaningful: would it fulfil its core competence of finding videos and streaming them to the browser?
Youtube actually uses this capability specifically. If you add a Youtube video to a queue, it switches to a picture in picture mode where you can navigate while the video is still playing.
The only other technical challenge is handling animations between route changes. There's a browser api in progress (the shared element transition API) [2], that will allow animations during navigations without client side routing, but it still requires Javascript. Navigation animations are arguably just purely aesthetic though.
[1] https://youtu.be/860d8usGC0o?t=299
[2] https://developer.chrome.com/blog/shared-element-transitions...
Even things like voting and commenting are fairly straightforward to do basically, though you could do vastly better with an auto-resizing iframe (https://github.com/whatwg/html/issues/555) which would basically allow you to load new content into the document with a click (though it’ll clutter the history and make the back button behave surprisingly, see also https://github.com/whatwg/html/issues/6501 on that).