And while I would be willing to agree provisionally that most data (by volume of unique URLS) on the web does fit the document metaphor, if page views is your metric I'm not at all convinced.
For example, is it logical to even attempt to reason about a Facebook wall containing recent updates from $n individuals in terms of authorship? Is this even relevant information given the entire contents of the page will have changed in 12 hours?
The document metaphor made perfect sense 15 years ago but it breaks down quickly in the face anything dynamic, as is evidenced by the need for any credible web developer to have a minimum of 7 largely unrelated technologies[2] committed to memory to do their job effectively.
Markup 15 layers deep? 2000+ lines of code to tell the browser how to render a website? Vendor-specific dynamic rendering engines to sidestep the limitations of native web languages? Surely this is not what success looks like?
[1] Unfortunately I have no idea how to fix this mess.
[2] HTML, CSS, JavaScript, a JS Framework (typically jQuery), at least one back-end language, SQL or similar and API stuff (SOAP, JSON, etc).