The only other person in this conversation is you, so not exactly the most representative of samples, but it is an interesting perspective. I've not heard anyone else consider the same HTML resource to be more than one page before. In fact, the term "single page application" hinges on a single HTML resource in the same way. The application may have more than one screen of content, but it is still considered one page.
oxnrtr is in this conversation too. And when describing the length of a document, "pages" universally means the number of printed pages it would occupy, not the number of computer files it's stored in.
There is no sign of anyone else participating in this conversation. Else we'd have heard their input by now. A page referring to a single HTML resource is standard nomenclature. Paper is antiquated technology, not how the Go specification is distributed, and carries no relevance to this discussion.