Both those methods rely on the browser not prefetching certain resources, which they are absolutely allowed to prefetch. So if a browser changes the prefetchin

Both those methods rely on the browser not prefetching certain resources, which they are absolutely allowed to prefetch. So if a browser changes the prefetching algo, the method is immediately broken. (For example enabling network.predictor.enable-prefetch in Firefox). It isn't an inherent weakness of CSS itself.