Yup.
> Webrings require ALL the web-administrators in the ring to keep their previous-and-next links up-to-date, otherwise the whole ring collapses.
Nope. Not then, when IFRAMEs or a pre-CORS AJAX call delegated ring maintenance upstream, and not now, when we have about 1500 more ways to delegate it. Was there a short period where they were as crude as you describe? Sure, but that's not really relevant to the forward-looking discussion of what they would look like now or the backward-looking discussion of what they looked like in the many years where they were mature and popular.