Having written two apps that do this, I can confirm that it is an amazing technique, and criminally underutilized! My projects store and render entire pages from the URL and encrypt URLs (respectively):
Hadn't considered it originally because I was concerned about allowable characters in the URL, and jumped to base64 instead of leaning more heavily on the actual set of acceptable characters to make it readable.
In hindsight, this is a great thing to add to my next project that (inevitably) uses this technique, thanks!
https://github.com/jstrieb/urlpages
https://github.com/jstrieb/link-lock