If this got popular, and an administrator wanted to disable comments, one thing that they could do is add a unique random prefix to every request to a URL. The web server would just generate a random prefix for each link it produces, and strip the random prefix from the path in every request it receives.
If the content is to be found via search engines, then this may not be advisable, and the plugin owner could try the same techniques that say Google would to use the canonical URL.
For example, HN's front page contains a set of URLs for each item. This item would be https://news.ycombinator.com/b149012c-56f4-4859-82b8-1f3f83e... for one request, and https://news.ycombinator.com/73e78d90-cc25-4091-8ffa-94783a2... for the next request. Both requests would get mapped to the same page, and serve up the same content (except with another uuid inserted into links).
Every comment would go into a unique SHA1 bucket and never seen again.