I think web developers are so used to URLs they don't realize how ridiculous they are. If you were inventing the web from scratch, there's no way you'd require a non-human-readable string displayed in the most prominent position on every single page and it's editable! How do people know how to edit it? Each site has its own unique undocumented parameters and formatting. It tells you something about the state of the page but not everything needed to debug problems. Also, don't make a SPA with an unchanging URL because you'll lose all the "important" value of a URL.

Desktop and mobile apps somehow survive without them. If URLs are important, why don't developers include their own URL system in those?