Why can you print to PDF but not to SVG?
Because PDF has the notion of pages, while SVG does not.
PDF and SVG are competing formats. Both are scalable without loss of resolution.
PDF was invented at Adobe. It displays documents portably, that is, the same on all platforms. It originally was mostly about text documents, which are paginated. Thus the notion of pages is built into PDF.
SVG displays a drawing portably (again, the same on all platforms.) But a drawing that can be scaled does not need pagination, when displayed on a computer screen. You can just pan, and zoom in and out on the one drawing.
It is only when you want to print an SVG to paper that you need worry about pagination. But whatever choice of pagination you make at printing time cannot be saved in a SVG file. (There exists a proposal to add pagination to the SVG standard.)
(PDF stands for Portable Document Format. A Document object often supports pagination.)