Except that URL's (visible pages) often don't map 1-1 to "content", and while they originally were "supposed" to, reality is far more complicated than that.
People like to be able to browse pages in an "intuitive" way. This means often combining multiple pieces of content onto a single page, or splitting up a single piece of content onto multiple pages, or often both.
In the real world, URL's are human-friendly pages which generally try to hit a sweet spot between too little and too much visible information, not unique identifiers of logical content.
Which is exactly why API's are useful -- they are designed around accessing logical content. But this is not what normal human-readable webpages are generally designed for, and rightfully so. They serve different purposes, and insisting that they should be the same is just silly.
It doesn't have to be a 1:1 mapping; there are certainly valid scenarios where it might not make sense (or it might be prohibitively difficult) to provide a particular representation of a particular resource, but that doesn't mean you shouldn't use consistent URLs where possible. This is what HTTP 406[1] is for.
The author's point is that URLs are not pages -- they are just pointers to information, and that (a) by design, they should be static and uniform, and (b) there is no reason that URLs cannot be used for both person- and machine-readable information.
People like to be able to browse pages in an "intuitive" way. This means often combining multiple pieces of content onto a single page, or splitting up a single piece of content onto multiple pages, or often both.
In the real world, URL's are human-friendly pages which generally try to hit a sweet spot between too little and too much visible information, not unique identifiers of logical content.
Which is exactly why API's are useful -- they are designed around accessing logical content. But this is not what normal human-readable webpages are generally designed for, and rightfully so. They serve different purposes, and insisting that they should be the same is just silly.