Isn’t this all as simple as cosmetically filtering elements like before? The Content Blocking API used by Safari for instance can be fed per-tag rather than per-file blocks. I add block rules to do this all the time to get rid of things like toolbars and login buttons on sites like YouTube and anime streaming sites. Besides, standards like these can’t be properly applied to dynamic content anyway, so the original pages have to stick around, which means one can simply use the original URL which still has to be there.
...and if the World Wide Web does get death by a thousand cuts as a result, then hurrah! We need a greater diversity of protocols for our applications and maybe, just maybe, gopher sites will make a comeback.